ffmpeg.c

// This does not quite work like avcodec_decode_audio4/avcodec_decode_video2.
// There is the following difference: if you got a frame, you must call
// it again with pkt=NULL. pkt==NULL is treated differently from pkt.size==0
// (pkt==NULL means get more output, pkt.size==0 is a flush/drain packet)
static int decode(AVCodecContext *avctx, AVFrame *frame, int *got_frame, AVPacket *pkt)
{
    int ret;

    *got_frame = 0;

    if (pkt) {
        ret = avcodec_send_packet(avctx, pkt);
        // In particular, we don't expect AVERROR(EAGAIN), because we read all
        // decoded frames with avcodec_receive_frame() until done.
        if (ret < 0 && ret != AVERROR_EOF)
            return ret;
    }

    ret = avcodec_receive_frame(avctx, frame);
    if (ret < 0 && ret != AVERROR(EAGAIN))
        return ret;
    if (ret >= 0)
        *got_frame = 1;

    return 0;
}

static int decode_audio(InputStream *ist, AVPacket *pkt, int *got_output)
{
    AVFrame *decoded_frame, *f;
    AVCodecContext *avctx = ist->dec_ctx;
    int i, ret, err = 0, resample_changed;
    AVRational decoded_frame_tb;

    if (!ist->decoded_frame && !(ist->decoded_frame = av_frame_alloc()))
        return AVERROR(ENOMEM);
    if (!ist->filter_frame && !(ist->filter_frame = av_frame_alloc()))
        return AVERROR(ENOMEM);
    decoded_frame = ist->decoded_frame;

    update_benchmark(NULL);
    ret = decode(avctx, decoded_frame, got_output, pkt);
    update_benchmark("decode_audio %d.%d", ist->file_index, ist->st->index);

    if (ret >= 0 && avctx->sample_rate <= 0) {
        av_log(avctx, AV_LOG_ERROR, "Sample rate %d invalid\n", avctx->sample_rate);
        ret = AVERROR_INVALIDDATA;
    }

    if (ret != AVERROR_EOF)
        check_decode_result(ist, got_output, ret);

    if (!*got_output || ret < 0)
        return ret;

    ist->samples_decoded += decoded_frame->nb_samples;
    ist->frames_decoded++;

#if 1
    /* increment next_dts to use for the case where the input stream does not
       have timestamps or there are multiple frames in the packet */
    ist->next_pts += ((int64_t)AV_TIME_BASE * decoded_frame->nb_samples) /
                     avctx->sample_rate;
    ist->next_dts += ((int64_t)AV_TIME_BASE * decoded_frame->nb_samples) /
                     avctx->sample_rate;
#endif

    resample_changed = ist->resample_sample_fmt     != decoded_frame->format         ||
                       ist->resample_channels       != avctx->channels               ||
                       ist->resample_channel_layout != decoded_frame->channel_layout ||
                       ist->resample_sample_rate    != decoded_frame->sample_rate;
    if (resample_changed) {
        char layout1[64], layout2[64];

        if (!guess_input_channel_layout(ist)) {
            av_log(NULL, AV_LOG_FATAL, "Unable to find default channel "
                   "layout for Input Stream #%d.%d\n", ist->file_index,
                   ist->st->index);
            exit_program(1);
        }
        decoded_frame->channel_layout = avctx->channel_layout;

        av_get_channel_layout_string(layout1, sizeof(layout1), ist->resample_channels,
                                     ist->resample_channel_layout);
        av_get_channel_layout_string(layout2, sizeof(layout2), avctx->channels,
                                     decoded_frame->channel_layout);

        av_log(NULL, AV_LOG_INFO,
               "Input stream #%d:%d frame changed from rate:%d fmt:%s ch:%d chl:%s to rate:%d fmt:%s ch:%d chl:%s\n",
               ist->file_index, ist->st->index,
               ist->resample_sample_rate,  av_get_sample_fmt_name(ist->resample_sample_fmt),
               ist->resample_channels, layout1,
               decoded_frame->sample_rate, av_get_sample_fmt_name(decoded_frame->format),
               avctx->channels, layout2);

        ist->resample_sample_fmt     = decoded_frame->format;
        ist->resample_sample_rate    = decoded_frame->sample_rate;
        ist->resample_channel_layout = decoded_frame->channel_layout;
        ist->resample_channels       = avctx->channels;

        for (i = 0; i < nb_filtergraphs; i++)
            if (ist_in_filtergraph(filtergraphs[i], ist)) {
                FilterGraph *fg = filtergraphs[i];
                if (configure_filtergraph(fg) < 0) {
                    av_log(NULL, AV_LOG_FATAL, "Error reinitializing filters!\n");
                    exit_program(1);
                }
            }
    }

    if (decoded_frame->pts != AV_NOPTS_VALUE) {
        decoded_frame_tb   = ist->st->time_base;
    } else if (pkt && pkt->pts != AV_NOPTS_VALUE) {
        decoded_frame->pts = pkt->pts;
        decoded_frame_tb   = ist->st->time_base;
    }else {
        decoded_frame->pts = ist->dts;
        decoded_frame_tb   = AV_TIME_BASE_Q;
    }
    if (decoded_frame->pts != AV_NOPTS_VALUE)
        decoded_frame->pts = av_rescale_delta(decoded_frame_tb, decoded_frame->pts,
                                              (AVRational){1, avctx->sample_rate}, decoded_frame->nb_samples, &ist->filter_in_rescale_delta_last,
                                              (AVRational){1, avctx->sample_rate});
    ist->nb_samples = decoded_frame->nb_samples;
    for (i = 0; i < ist->nb_filters; i++) {
        if (i < ist->nb_filters - 1) {
            f = ist->filter_frame;
            err = av_frame_ref(f, decoded_frame);
            if (err < 0)
                break;
        } else
            f = decoded_frame;
        err = av_buffersrc_add_frame_flags(ist->filters[i]->filter, f,
                                     AV_BUFFERSRC_FLAG_PUSH);
        if (err == AVERROR_EOF)
            err = 0; /* ignore */
        if (err < 0)
            break;
    }
    decoded_frame->pts = AV_NOPTS_VALUE;

    av_frame_unref(ist->filter_frame);
    av_frame_unref(decoded_frame);
    return err < 0 ? err : ret;
}

static int decode_video(InputStream *ist, AVPacket *pkt, int *got_output, int eof)
{
    AVFrame *decoded_frame, *f;
    int i, ret = 0, err = 0, resample_changed;
    int64_t best_effort_timestamp;
    int64_t dts = AV_NOPTS_VALUE;
    AVRational *frame_sample_aspect;
    AVPacket avpkt;

    // With fate-indeo3-2, we're getting 0-sized packets before EOF for some
    // reason. This seems like a semi-critical bug. Don't trigger EOF, and
    // skip the packet.
    if (!eof && pkt && pkt->size == 0)
        return 0;

    if (!ist->decoded_frame && !(ist->decoded_frame = av_frame_alloc()))
        return AVERROR(ENOMEM);
    if (!ist->filter_frame && !(ist->filter_frame = av_frame_alloc()))
        return AVERROR(ENOMEM);
    decoded_frame = ist->decoded_frame;
    if (ist->dts != AV_NOPTS_VALUE)
        dts = av_rescale_q(ist->dts, AV_TIME_BASE_Q, ist->st->time_base);
    if (pkt) {
        avpkt = *pkt;
        avpkt.dts = dts; // ffmpeg.c probably shouldn't do this
    }

    // The old code used to set dts on the drain packet, which does not work
    // with the new API anymore.
    if (eof) {
        void *new = av_realloc_array(ist->dts_buffer, ist->nb_dts_buffer + 1, sizeof(ist->dts_buffer[0]));
        if (!new)
            return AVERROR(ENOMEM);
        ist->dts_buffer = new;
        ist->dts_buffer[ist->nb_dts_buffer++] = dts;
    }

    update_benchmark(NULL);
    ret = decode(ist->dec_ctx, decoded_frame, got_output, pkt ? &avpkt : NULL);
    update_benchmark("decode_video %d.%d", ist->file_index, ist->st->index);

    // The following line may be required in some cases where there is no parser
    // or the parser does not has_b_frames correctly
    if (ist->st->codecpar->video_delay < ist->dec_ctx->has_b_frames) {
        if (ist->dec_ctx->codec_id == AV_CODEC_ID_H264) {
            ist->st->codecpar->video_delay = ist->dec_ctx->has_b_frames;
        } else
            av_log(ist->dec_ctx, AV_LOG_WARNING,
                   "video_delay is larger in decoder than demuxer %d > %d.\n"
                   "If you want to help, upload a sample "
                   "of this file to ftp://upload.ffmpeg.org/incoming/ "
                   "and contact the ffmpeg-devel mailing list. (ffmpeg-devel@ffmpeg.org)",
                   ist->dec_ctx->has_b_frames,
                   ist->st->codecpar->video_delay);
    }

    if (ret != AVERROR_EOF)
        check_decode_result(ist, got_output, ret);

    if (*got_output && ret >= 0) {
        if (ist->dec_ctx->width  != decoded_frame->width ||
            ist->dec_ctx->height != decoded_frame->height ||
            ist->dec_ctx->pix_fmt != decoded_frame->format) {
            av_log(NULL, AV_LOG_DEBUG, "Frame parameters mismatch context %d,%d,%d != %d,%d,%d\n",
                decoded_frame->width,
                decoded_frame->height,
                decoded_frame->format,
                ist->dec_ctx->width,
                ist->dec_ctx->height,
                ist->dec_ctx->pix_fmt);
        }
    }

    if (!*got_output || ret < 0)
        return ret;

    if(ist->top_field_first>=0)
        decoded_frame->top_field_first = ist->top_field_first;

    ist->frames_decoded++;

    if (ist->hwaccel_retrieve_data && decoded_frame->format == ist->hwaccel_pix_fmt) {
        err = ist->hwaccel_retrieve_data(ist->dec_ctx, decoded_frame);
        if (err < 0)
            goto fail;
    }
    ist->hwaccel_retrieved_pix_fmt = decoded_frame->format;

    best_effort_timestamp= av_frame_get_best_effort_timestamp(decoded_frame);

    if (eof && best_effort_timestamp == AV_NOPTS_VALUE && ist->nb_dts_buffer > 0) {
        best_effort_timestamp = ist->dts_buffer[0];

        for (i = 0; i < ist->nb_dts_buffer - 1; i++)
            ist->dts_buffer[i] = ist->dts_buffer[i + 1];
        ist->nb_dts_buffer--;
    }

    if(best_effort_timestamp != AV_NOPTS_VALUE) {
        int64_t ts = av_rescale_q(decoded_frame->pts = best_effort_timestamp, ist->st->time_base, AV_TIME_BASE_Q);

        if (ts != AV_NOPTS_VALUE)
            ist->next_pts = ist->pts = ts;
    }

    if (debug_ts) {
        av_log(NULL, AV_LOG_INFO, "decoder -> ist_index:%d type:video "
               "frame_pts:%s frame_pts_time:%s best_effort_ts:%"PRId64" best_effort_ts_time:%s keyframe:%d frame_type:%d time_base:%d/%d\n",
               ist->st->index, av_ts2str(decoded_frame->pts),
               av_ts2timestr(decoded_frame->pts, &ist->st->time_base),
               best_effort_timestamp,
               av_ts2timestr(best_effort_timestamp, &ist->st->time_base),
               decoded_frame->key_frame, decoded_frame->pict_type,
               ist->st->time_base.num, ist->st->time_base.den);
    }

    if (ist->st->sample_aspect_ratio.num)
        decoded_frame->sample_aspect_ratio = ist->st->sample_aspect_ratio;

    resample_changed = ist->resample_width   != decoded_frame->width  ||
                       ist->resample_height  != decoded_frame->height ||
                       ist->resample_pix_fmt != decoded_frame->format;
    if (resample_changed) {
        av_log(NULL, AV_LOG_INFO,
               "Input stream #%d:%d frame changed from size:%dx%d fmt:%s to size:%dx%d fmt:%s\n",
               ist->file_index, ist->st->index,
               ist->resample_width,  ist->resample_height,  av_get_pix_fmt_name(ist->resample_pix_fmt),
               decoded_frame->width, decoded_frame->height, av_get_pix_fmt_name(decoded_frame->format));

        ist->resample_width   = decoded_frame->width;
        ist->resample_height  = decoded_frame->height;
        ist->resample_pix_fmt = decoded_frame->format;

        for (i = 0; i < nb_filtergraphs; i++) {
            if (ist_in_filtergraph(filtergraphs[i], ist) && ist->reinit_filters &&
                configure_filtergraph(filtergraphs[i]) < 0) {
                av_log(NULL, AV_LOG_FATAL, "Error reinitializing filters!\n");
                exit_program(1);
            }
        }
    }

    frame_sample_aspect= av_opt_ptr(avcodec_get_frame_class(), decoded_frame, "sample_aspect_ratio");
    for (i = 0; i < ist->nb_filters; i++) {
        if (!frame_sample_aspect->num)
            *frame_sample_aspect = ist->st->sample_aspect_ratio;

        if (i < ist->nb_filters - 1) {
            f = ist->filter_frame;
            err = av_frame_ref(f, decoded_frame);
            if (err < 0)
                break;
        } else
            f = decoded_frame;
        err = av_buffersrc_add_frame_flags(ist->filters[i]->filter, f, AV_BUFFERSRC_FLAG_PUSH);
        if (err == AVERROR_EOF) {
            err = 0; /* ignore */
        } else if (err < 0) {
            av_log(NULL, AV_LOG_FATAL,
                   "Failed to inject frame into filter network: %s\n", av_err2str(err));
            exit_program(1);
        }
    }

fail:
    av_frame_unref(ist->filter_frame);
    av_frame_unref(decoded_frame);
    return err < 0 ? err : ret;
}

static int transcode_subtitles(InputStream *ist, AVPacket *pkt, int *got_output)
{
    AVSubtitle subtitle;
    int i, ret = avcodec_decode_subtitle2(ist->dec_ctx,
                                          &subtitle, got_output, pkt);

    check_decode_result(NULL, got_output, ret);

    if (ret < 0 || !*got_output) {
        if (!pkt->size)
            sub2video_flush(ist);
        return ret;
    }

    if (ist->fix_sub_duration) {
        int end = 1;
        if (ist->prev_sub.got_output) {
            end = av_rescale(subtitle.pts - ist->prev_sub.subtitle.pts,
                             1000, AV_TIME_BASE);
            if (end < ist->prev_sub.subtitle.end_display_time) {
                av_log(ist->dec_ctx, AV_LOG_DEBUG,
                       "Subtitle duration reduced from %d to %d%s\n",
                       ist->prev_sub.subtitle.end_display_time, end,
                       end <= 0 ? ", dropping it" : "");
                ist->prev_sub.subtitle.end_display_time = end;
            }
        }
        FFSWAP(int,        *got_output, ist->prev_sub.got_output);
        FFSWAP(int,        ret,         ist->prev_sub.ret);
        FFSWAP(AVSubtitle, subtitle,    ist->prev_sub.subtitle);
        if (end <= 0)
            goto out;
    }

    if (!*got_output)
        return ret;

    sub2video_update(ist, &subtitle);

    if (!subtitle.num_rects)
        goto out;

    ist->frames_decoded++;

    for (i = 0; i < nb_output_streams; i++) {
        OutputStream *ost = output_streams[i];

        if (!check_output_constraints(ist, ost) || !ost->encoding_needed
            || ost->enc->type != AVMEDIA_TYPE_SUBTITLE)
            continue;

        do_subtitle_out(output_files[ost->file_index]->ctx, ost, ist, &subtitle);
    }

out:
    avsubtitle_free(&subtitle);
    return ret;
}

static int send_filter_eof(InputStream *ist)
{
    int i, ret;
    for (i = 0; i < ist->nb_filters; i++) {
        ret = av_buffersrc_add_frame(ist->filters[i]->filter, NULL);
        if (ret < 0)
            return ret;
    }
    return 0;
}

/* pkt = NULL means EOF (needed to flush decoder buffers) */
static int process_input_packet(InputStream *ist, const AVPacket *pkt, int no_eof)
{
    int ret = 0, i;
    int repeating = 0;
    int eof_reached = 0;

    AVPacket avpkt;
    if (!ist->saw_first_ts) {
        ist->dts = ist->st->avg_frame_rate.num ? - ist->dec_ctx->has_b_frames * AV_TIME_BASE / av_q2d(ist->st->avg_frame_rate) : 0;
        ist->pts = 0;
        if (pkt && pkt->pts != AV_NOPTS_VALUE && !ist->decoding_needed) {
            ist->dts += av_rescale_q(pkt->pts, ist->st->time_base, AV_TIME_BASE_Q);
            ist->pts = ist->dts; //unused but better to set it to a value thats not totally wrong
        }
        ist->saw_first_ts = 1;
    }

    if (ist->next_dts == AV_NOPTS_VALUE)
        ist->next_dts = ist->dts;
    if (ist->next_pts == AV_NOPTS_VALUE)
        ist->next_pts = ist->pts;

    if (!pkt) {
        /* EOF handling */
        av_init_packet(&avpkt);
        avpkt.data = NULL;
        avpkt.size = 0;
    } else {
        avpkt = *pkt;
    }

    if (pkt && pkt->dts != AV_NOPTS_VALUE) {
        ist->next_dts = ist->dts = av_rescale_q(pkt->dts, ist->st->time_base, AV_TIME_BASE_Q);
        if (ist->dec_ctx->codec_type != AVMEDIA_TYPE_VIDEO || !ist->decoding_needed)
            ist->next_pts = ist->pts = ist->dts;
    }

    // while we have more to decode or while the decoder did output something on EOF
    while (ist->decoding_needed) {
        int duration = 0;
        int got_output = 0;

        ist->pts = ist->next_pts;
        ist->dts = ist->next_dts;

        switch (ist->dec_ctx->codec_type) {
        case AVMEDIA_TYPE_AUDIO:
            ret = decode_audio    (ist, repeating ? NULL : &avpkt, &got_output);
            break;
        case AVMEDIA_TYPE_VIDEO:
            ret = decode_video    (ist, repeating ? NULL : &avpkt, &got_output, !pkt);
            if (!repeating || !pkt || got_output) {
                if (pkt && pkt->duration) {
                    duration = av_rescale_q(pkt->duration, ist->st->time_base, AV_TIME_BASE_Q);
                } else if(ist->dec_ctx->framerate.num != 0 && ist->dec_ctx->framerate.den != 0) {
                    int ticks= av_stream_get_parser(ist->st) ? av_stream_get_parser(ist->st)->repeat_pict+1 : ist->dec_ctx->ticks_per_frame;
                    duration = ((int64_t)AV_TIME_BASE *
                                    ist->dec_ctx->framerate.den * ticks) /
                                    ist->dec_ctx->framerate.num / ist->dec_ctx->ticks_per_frame;
                }

                if(ist->dts != AV_NOPTS_VALUE && duration) {
                    ist->next_dts += duration;
                }else
                    ist->next_dts = AV_NOPTS_VALUE;
            }

            if (got_output)
                ist->next_pts += duration; //FIXME the duration is not correct in some cases
            break;
        case AVMEDIA_TYPE_SUBTITLE:
            if (repeating)
                break;
            ret = transcode_subtitles(ist, &avpkt, &got_output);
            if (!pkt && ret >= 0)
                ret = AVERROR_EOF;
            break;
        default:
            return -1;
        }

        if (ret == AVERROR_EOF) {
            eof_reached = 1;
            break;
        }

        if (ret < 0) {
            av_log(NULL, AV_LOG_ERROR, "Error while decoding stream #%d:%d: %s\n",
                   ist->file_index, ist->st->index, av_err2str(ret));
            if (exit_on_error)
                exit_program(1);
            // Decoding might not terminate if we're draining the decoder, and
            // the decoder keeps returning an error.
            // This should probably be considered a libavcodec issue.
            // Sample: fate-vsynth1-dnxhd-720p-hr-lb
            if (!pkt)
                eof_reached = 1;
            break;
        }

        if (!got_output)
            break;

        // During draining, we might get multiple output frames in this loop.
        // ffmpeg.c does not drain the filter chain on configuration changes,
        // which means if we send multiple frames at once to the filters, and
        // one of those frames changes configuration, the buffered frames will
        // be lost. This can upset certain FATE tests.
        // Decode only 1 frame per call on EOF to appease these FATE tests.
        // The ideal solution would be to rewrite decoding to use the new
        // decoding API in a better way.
        if (!pkt)
            break;

        repeating = 1;
    }

    /* after flushing, send an EOF on all the filter inputs attached to the stream */
    /* except when looping we need to flush but not to send an EOF */
    if (!pkt && ist->decoding_needed && eof_reached && !no_eof) {
        int ret = send_filter_eof(ist);
        if (ret < 0) {
            av_log(NULL, AV_LOG_FATAL, "Error marking filters as finished\n");
            exit_program(1);
        }
    }

    /* handle stream copy */
    if (!ist->decoding_needed) {
        ist->dts = ist->next_dts;
        switch (ist->dec_ctx->codec_type) {
        case AVMEDIA_TYPE_AUDIO:
            ist->next_dts += ((int64_t)AV_TIME_BASE * ist->dec_ctx->frame_size) /
                             ist->dec_ctx->sample_rate;
            break;
        case AVMEDIA_TYPE_VIDEO:
            if (ist->framerate.num) {
                // TODO: Remove work-around for c99-to-c89 issue 7
                AVRational time_base_q = AV_TIME_BASE_Q;
                int64_t next_dts = av_rescale_q(ist->next_dts, time_base_q, av_inv_q(ist->framerate));
                ist->next_dts = av_rescale_q(next_dts + 1, av_inv_q(ist->framerate), time_base_q);
            } else if (pkt->duration) {
                ist->next_dts += av_rescale_q(pkt->duration, ist->st->time_base, AV_TIME_BASE_Q);
            } else if(ist->dec_ctx->framerate.num != 0) {
                int ticks= av_stream_get_parser(ist->st) ? av_stream_get_parser(ist->st)->repeat_pict + 1 : ist->dec_ctx->ticks_per_frame;
                ist->next_dts += ((int64_t)AV_TIME_BASE *
                                  ist->dec_ctx->framerate.den * ticks) /
                                  ist->dec_ctx->framerate.num / ist->dec_ctx->ticks_per_frame;
            }
            break;
        }
        ist->pts = ist->dts;
        ist->next_pts = ist->next_dts;
    }
    for (i = 0; pkt && i < nb_output_streams; i++) {
        OutputStream *ost = output_streams[i];

        if (!check_output_constraints(ist, ost) || ost->encoding_needed)
            continue;

        do_streamcopy(ist, ost, pkt);
    }

    return !eof_reached;
}

static void print_sdp(void)
{
    char sdp[16384];
    int i;
    int j;
    AVIOContext *sdp_pb;
    AVFormatContext **avc = av_malloc_array(nb_output_files, sizeof(*avc));

    if (!avc)
        exit_program(1);
    for (i = 0, j = 0; i < nb_output_files; i++) {
        if (!strcmp(output_files[i]->ctx->oformat->name, "rtp")) {
            avc[j] = output_files[i]->ctx;
            j++;
        }
    }

    if (!j)
        goto fail;

    av_sdp_create(avc, j, sdp, sizeof(sdp));

    if (!sdp_filename) {
        printf("SDP:\n%s\n", sdp);
        fflush(stdout);
    } else {
        if (avio_open2(&sdp_pb, sdp_filename, AVIO_FLAG_WRITE, &int_cb, NULL) < 0) {
            av_log(NULL, AV_LOG_ERROR, "Failed to open sdp file '%s'\n", sdp_filename);
        } else {
            avio_printf(sdp_pb, "SDP:\n%s", sdp);
            avio_closep(&sdp_pb);
            av_freep(&sdp_filename);
        }
    }

fail:
    av_freep(&avc);
}

static const HWAccel *get_hwaccel(enum AVPixelFormat pix_fmt)
{
    int i;
    for (i = 0; hwaccels[i].name; i++)
        if (hwaccels[i].pix_fmt == pix_fmt)
            return &hwaccels[i];
    return NULL;
}

static enum AVPixelFormat get_format(AVCodecContext *s, const enum AVPixelFormat *pix_fmts)
{
    InputStream *ist = s->opaque;
    const enum AVPixelFormat *p;
    int ret;

    for (p = pix_fmts; *p != -1; p++) {
        const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(*p);
        const HWAccel *hwaccel;

        if (!(desc->flags & AV_PIX_FMT_FLAG_HWACCEL))
            break;

        hwaccel = get_hwaccel(*p);
        if (!hwaccel ||
            (ist->active_hwaccel_id && ist->active_hwaccel_id != hwaccel->id) ||
            (ist->hwaccel_id != HWACCEL_AUTO && ist->hwaccel_id != hwaccel->id))
            continue;

        ret = hwaccel->init(s);
        if (ret < 0) {
            if (ist->hwaccel_id == hwaccel->id) {
                av_log(NULL, AV_LOG_FATAL,
                       "%s hwaccel requested for input stream #%d:%d, "
                       "but cannot be initialized.\n", hwaccel->name,
                       ist->file_index, ist->st->index);
                return AV_PIX_FMT_NONE;
            }
            continue;
        }

        if (ist->hw_frames_ctx) {
            s->hw_frames_ctx = av_buffer_ref(ist->hw_frames_ctx);
            if (!s->hw_frames_ctx)
                return AV_PIX_FMT_NONE;
        }

        ist->active_hwaccel_id = hwaccel->id;
        ist->hwaccel_pix_fmt   = *p;
        break;
    }

    return *p;
}

static int get_buffer(AVCodecContext *s, AVFrame *frame, int flags)
{
    InputStream *ist = s->opaque;

    if (ist->hwaccel_get_buffer && frame->format == ist->hwaccel_pix_fmt)
        return ist->hwaccel_get_buffer(s, frame, flags);

    return avcodec_default_get_buffer2(s, frame, flags);
}

static int init_input_stream(int ist_index, char *error, int error_len)
{
    int ret;
    InputStream *ist = input_streams[ist_index];

    if (ist->decoding_needed) {
        AVCodec *codec = ist->dec;
        if (!codec) {
            snprintf(error, error_len, "Decoder (codec %s) not found for input stream #%d:%d",
                    avcodec_get_name(ist->dec_ctx->codec_id), ist->file_index, ist->st->index);
            return AVERROR(EINVAL);
        }

        ist->dec_ctx->opaque                = ist;
        ist->dec_ctx->get_format            = get_format;
        ist->dec_ctx->get_buffer2           = get_buffer;
        ist->dec_ctx->thread_safe_callbacks = 1;

        av_opt_set_int(ist->dec_ctx, "refcounted_frames", 1, 0);
        if (ist->dec_ctx->codec_id == AV_CODEC_ID_DVB_SUBTITLE &&
           (ist->decoding_needed & DECODING_FOR_OST)) {
            av_dict_set(&ist->decoder_opts, "compute_edt", "1", AV_DICT_DONT_OVERWRITE);
            if (ist->decoding_needed & DECODING_FOR_FILTER)
                av_log(NULL, AV_LOG_WARNING, "Warning using DVB subtitles for filtering and output at the same time is not fully supported, also see -compute_edt [0|1]\n");
        }

        av_dict_set(&ist->decoder_opts, "sub_text_format", "ass", AV_DICT_DONT_OVERWRITE);

        /* Useful for subtitles retiming by lavf (FIXME), skipping samples in
         * audio, and video decoders such as cuvid or mediacodec */
        av_codec_set_pkt_timebase(ist->dec_ctx, ist->st->time_base);

        if (!av_dict_get(ist->decoder_opts, "threads", NULL, 0))
            av_dict_set(&ist->decoder_opts, "threads", "auto", 0);
        if ((ret = avcodec_open2(ist->dec_ctx, codec, &ist->decoder_opts)) < 0) {
            if (ret == AVERROR_EXPERIMENTAL)
                abort_codec_experimental(codec, 0);

            snprintf(error, error_len,
                     "Error while opening decoder for input stream "
                     "#%d:%d : %s",
                     ist->file_index, ist->st->index, av_err2str(ret));
            return ret;
        }
        assert_avoptions(ist->decoder_opts);
    }

    ist->next_pts = AV_NOPTS_VALUE;
    ist->next_dts = AV_NOPTS_VALUE;

    return 0;
}

static InputStream *get_input_stream(OutputStream *ost)
{
    if (ost->source_index >= 0)
        return input_streams[ost->source_index];
    return NULL;
}

static int compare_int64(const void *a, const void *b)
{
    return FFDIFFSIGN(*(const int64_t *)a, *(const int64_t *)b);
}

static int init_output_bsfs(OutputStream *ost)
{
    AVBSFContext *ctx;
    int i, ret;

    if (!ost->nb_bitstream_filters)
        return 0;

    for (i = 0; i < ost->nb_bitstream_filters; i++) {
        ctx = ost->bsf_ctx[i];

        ret = avcodec_parameters_copy(ctx->par_in,
                                      i ? ost->bsf_ctx[i - 1]->par_out : ost->st->codecpar);
        if (ret < 0)
            return ret;

        ctx->time_base_in = i ? ost->bsf_ctx[i - 1]->time_base_out : ost->st->time_base;

        ret = av_bsf_init(ctx);
        if (ret < 0) {
            av_log(NULL, AV_LOG_ERROR, "Error initializing bitstream filter: %s\n",
                   ost->bsf_ctx[i]->filter->name);
            return ret;
        }
    }

    ctx = ost->bsf_ctx[ost->nb_bitstream_filters - 1];
    ret = avcodec_parameters_copy(ost->st->codecpar, ctx->par_out);
    if (ret < 0)
        return ret;

    ost->st->time_base = ctx->time_base_out;

    return 0;
}

static int init_output_stream_streamcopy(OutputStream *ost)
{
    OutputFile *of = output_files[ost->file_index];
    InputStream *ist = get_input_stream(ost);
    AVCodecParameters *par_dst = ost->st->codecpar;
    AVCodecParameters *par_src = ost->ref_par;
    AVRational sar;
    int i, ret;
    uint64_t extra_size;

    av_assert0(ist && !ost->filter);

    avcodec_parameters_to_context(ost->enc_ctx, ist->st->codecpar);
    ret = av_opt_set_dict(ost->enc_ctx, &ost->encoder_opts);
    if (ret < 0) {
        av_log(NULL, AV_LOG_FATAL,
               "Error setting up codec context options.\n");
        return ret;
    }
    avcodec_parameters_from_context(par_src, ost->enc_ctx);

    extra_size = (uint64_t)par_src->extradata_size + AV_INPUT_BUFFER_PADDING_SIZE;

    if (extra_size > INT_MAX) {
        return AVERROR(EINVAL);
    }

    /* if stream_copy is selected, no need to decode or encode */
    par_dst->codec_id   = par_src->codec_id;
    par_dst->codec_type = par_src->codec_type;

    if (!par_dst->codec_tag) {
        unsigned int codec_tag;
        if (!of->ctx->oformat->codec_tag ||
            av_codec_get_id (of->ctx->oformat->codec_tag, par_src->codec_tag) == par_dst->codec_id ||
            !av_codec_get_tag2(of->ctx->oformat->codec_tag, par_src->codec_id, &codec_tag))
            par_dst->codec_tag = par_src->codec_tag;
    }

    par_dst->bit_rate        = par_src->bit_rate;
    par_dst->field_order     = par_src->field_order;
    par_dst->chroma_location = par_src->chroma_location;

    if (par_src->extradata_size) {
        par_dst->extradata      = av_mallocz(extra_size);
        if (!par_dst->extradata) {
            return AVERROR(ENOMEM);
        }
        memcpy(par_dst->extradata, par_src->extradata, par_src->extradata_size);
        par_dst->extradata_size = par_src->extradata_size;
    }
    par_dst->bits_per_coded_sample  = par_src->bits_per_coded_sample;
    par_dst->bits_per_raw_sample    = par_src->bits_per_raw_sample;

    if (!ost->frame_rate.num)
        ost->frame_rate = ist->framerate;
    ost->st->avg_frame_rate = ost->frame_rate;

    ret = avformat_transfer_internal_stream_timing_info(of->ctx->oformat, ost->st, ist->st, copy_tb);
    if (ret < 0)
        return ret;

    // copy timebase while removing common factors
    ost->st->time_base = av_add_q(av_stream_get_codec_timebase(ost->st), (AVRational){0, 1});

    if (ist->st->nb_side_data) {
        ost->st->side_data = av_realloc_array(NULL, ist->st->nb_side_data,
                                              sizeof(*ist->st->side_data));
        if (!ost->st->side_data)
            return AVERROR(ENOMEM);

        ost->st->nb_side_data = 0;
        for (i = 0; i < ist->st->nb_side_data; i++) {
            const AVPacketSideData *sd_src = &ist->st->side_data[i];
            AVPacketSideData *sd_dst = &ost->st->side_data[ost->st->nb_side_data];

            if (ost->rotate_overridden && sd_src->type == AV_PKT_DATA_DISPLAYMATRIX)
                continue;

            sd_dst->data = av_malloc(sd_src->size);
            if (!sd_dst->data)
                return AVERROR(ENOMEM);
            memcpy(sd_dst->data, sd_src->data, sd_src->size);
            sd_dst->size = sd_src->size;
            sd_dst->type = sd_src->type;
            ost->st->nb_side_data++;
        }
    }

    ost->parser = av_parser_init(par_dst->codec_id);
    ost->parser_avctx = avcodec_alloc_context3(NULL);
    if (!ost->parser_avctx)
        return AVERROR(ENOMEM);

    switch (par_dst->codec_type) {
    case AVMEDIA_TYPE_AUDIO:
        if (audio_volume != 256) {
            av_log(NULL, AV_LOG_FATAL, "-acodec copy and -vol are incompatible (frames are not decoded)\n");
            exit_program(1);
        }
        par_dst->channel_layout     = par_src->channel_layout;
        par_dst->sample_rate        = par_src->sample_rate;
        par_dst->channels           = par_src->channels;
        par_dst->frame_size         = par_src->frame_size;
        par_dst->block_align        = par_src->block_align;
        par_dst->initial_padding    = par_src->initial_padding;
        par_dst->trailing_padding   = par_src->trailing_padding;
        par_dst->profile            = par_src->profile;
        if((par_dst->block_align == 1 || par_dst->block_align == 1152 || par_dst->block_align == 576) && par_dst->codec_id == AV_CODEC_ID_MP3)
            par_dst->block_align= 0;
        if(par_dst->codec_id == AV_CODEC_ID_AC3)
            par_dst->block_align= 0;
        break;
    case AVMEDIA_TYPE_VIDEO:
        par_dst->format             = par_src->format;
        par_dst->color_space        = par_src->color_space;
        par_dst->color_range        = par_src->color_range;
        par_dst->color_primaries    = par_src->color_primaries;
        par_dst->color_trc          = par_src->color_trc;
        par_dst->width              = par_src->width;
        par_dst->height             = par_src->height;
        par_dst->video_delay        = par_src->video_delay;
        par_dst->profile            = par_src->profile;
        if (ost->frame_aspect_ratio.num) { // overridden by the -aspect cli option
            sar =
                av_mul_q(ost->frame_aspect_ratio,
                         (AVRational){ par_dst->height, par_dst->width });
            av_log(NULL, AV_LOG_WARNING, "Overriding aspect ratio "
                   "with stream copy may produce invalid files\n");
            }
        else if (ist->st->sample_aspect_ratio.num)
            sar = ist->st->sample_aspect_ratio;
        else
            sar = par_src->sample_aspect_ratio;
        ost->st->sample_aspect_ratio = par_dst->sample_aspect_ratio = sar;
        ost->st->avg_frame_rate = ist->st->avg_frame_rate;
        ost->st->r_frame_rate = ist->st->r_frame_rate;
        break;
    case AVMEDIA_TYPE_SUBTITLE:
        par_dst->width  = par_src->width;
        par_dst->height = par_src->height;
        break;
    case AVMEDIA_TYPE_UNKNOWN:
    case AVMEDIA_TYPE_DATA:
    case AVMEDIA_TYPE_ATTACHMENT:
        break;
    default:
        abort();
    }

    return 0;
}

static int init_output_stream(OutputStream *ost, char *error, int error_len)
{
    int ret = 0;

    if (ost->encoding_needed) {
        AVCodec      *codec = ost->enc;
        AVCodecContext *dec = NULL;
        InputStream *ist;

        if ((ist = get_input_stream(ost)))
            dec = ist->dec_ctx;
        if (dec && dec->subtitle_header) {
            /* ASS code assumes this buffer is null terminated so add extra byte. */
            ost->enc_ctx->subtitle_header = av_mallocz(dec->subtitle_header_size + 1);
            if (!ost->enc_ctx->subtitle_header)
                return AVERROR(ENOMEM);
            memcpy(ost->enc_ctx->subtitle_header, dec->subtitle_header, dec->subtitle_header_size);
            ost->enc_ctx->subtitle_header_size = dec->subtitle_header_size;
        }
        if (!av_dict_get(ost->encoder_opts, "threads", NULL, 0))
            av_dict_set(&ost->encoder_opts, "threads", "auto", 0);
        if (ost->enc->type == AVMEDIA_TYPE_AUDIO &&
            !codec->defaults &&
            !av_dict_get(ost->encoder_opts, "b", NULL, 0) &&
            !av_dict_get(ost->encoder_opts, "ab", NULL, 0))
            av_dict_set(&ost->encoder_opts, "b", "128000", 0);

        if (ost->filter && ost->filter->filter->inputs[0]->hw_frames_ctx) {
            ost->enc_ctx->hw_frames_ctx = av_buffer_ref(ost->filter->filter->inputs[0]->hw_frames_ctx);
            if (!ost->enc_ctx->hw_frames_ctx)
                return AVERROR(ENOMEM);
        }

        if ((ret = avcodec_open2(ost->enc_ctx, codec, &ost->encoder_opts)) < 0) {
            if (ret == AVERROR_EXPERIMENTAL)
                abort_codec_experimental(codec, 1);
            snprintf(error, error_len,
                     "Error while opening encoder for output stream #%d:%d - "
                     "maybe incorrect parameters such as bit_rate, rate, width or height",
                    ost->file_index, ost->index);
            return ret;
        }
        if (ost->enc->type == AVMEDIA_TYPE_AUDIO &&
            !(ost->enc->capabilities & AV_CODEC_CAP_VARIABLE_FRAME_SIZE))
            av_buffersink_set_frame_size(ost->filter->filter,
                                            ost->enc_ctx->frame_size);
        assert_avoptions(ost->encoder_opts);
        if (ost->enc_ctx->bit_rate && ost->enc_ctx->bit_rate < 1000)
            av_log(NULL, AV_LOG_WARNING, "The bitrate parameter is set too low."
                                         " It takes bits/s as argument, not kbits/s\n");

        ret = avcodec_parameters_from_context(ost->st->codecpar, ost->enc_ctx);
        if (ret < 0) {
            av_log(NULL, AV_LOG_FATAL,
                   "Error initializing the output stream codec context.\n");
            exit_program(1);
        }
        /*
         * FIXME: ost->st->codec should't be needed here anymore.
         */
        ret = avcodec_copy_context(ost->st->codec, ost->enc_ctx);
        if (ret < 0)
            return ret;

        if (ost->enc_ctx->nb_coded_side_data) {
            int i;

            ost->st->side_data = av_realloc_array(NULL, ost->enc_ctx->nb_coded_side_data,
                                                  sizeof(*ost->st->side_data));
            if (!ost->st->side_data)
                return AVERROR(ENOMEM);

            for (i = 0; i < ost->enc_ctx->nb_coded_side_data; i++) {
                const AVPacketSideData *sd_src = &ost->enc_ctx->coded_side_data[i];
                AVPacketSideData *sd_dst = &ost->st->side_data[i];

                sd_dst->data = av_malloc(sd_src->size);
                if (!sd_dst->data)
                    return AVERROR(ENOMEM);
                memcpy(sd_dst->data, sd_src->data, sd_src->size);
                sd_dst->size = sd_src->size;
                sd_dst->type = sd_src->type;
                ost->st->nb_side_data++;
            }
        }

        // copy timebase while removing common factors
        ost->st->time_base = av_add_q(ost->enc_ctx->time_base, (AVRational){0, 1});
        ost->st->codec->codec= ost->enc_ctx->codec;
    } else if (ost->stream_copy) {