utils.c

/*
 * various utility functions for use within Libav
 * Copyright (c) 2000, 2001, 2002 Fabrice Bellard
 *
 * This file is part of Libav.
 *
 * Libav is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * Libav is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with Libav; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

/* #define DEBUG */

#include "avformat.h"
#include "avio_internal.h"
#include "internal.h"
#include "libavcodec/internal.h"
#include "libavcodec/bytestream.h"
#include "libavutil/opt.h"
#include "libavutil/dict.h"
#include "libavutil/pixdesc.h"
#include "metadata.h"
#include "id3v2.h"
#include "libavutil/avassert.h"
#include "libavutil/avstring.h"
#include "libavutil/mathematics.h"
#include "libavutil/parseutils.h"
#include "libavutil/time.h"
#include "riff.h"
#include "audiointerleave.h"
#include "url.h"
#include <stdarg.h>
#if CONFIG_NETWORK
#include "network.h"
#endif

#undef NDEBUG
#include <assert.h>

/**
 * @file
 * various utility functions for use within Libav
 */

unsigned avformat_version(void)
{
    return LIBAVFORMAT_VERSION_INT;
}

const char *avformat_configuration(void)
{
    return LIBAV_CONFIGURATION;
}

const char *avformat_license(void)
{
#define LICENSE_PREFIX "libavformat license: "
    return LICENSE_PREFIX LIBAV_LICENSE + sizeof(LICENSE_PREFIX) - 1;
}

/* fraction handling */

/**
 * f = val + (num / den) + 0.5.
 *
 * 'num' is normalized so that it is such as 0 <= num < den.
 *
 * @param f fractional number
 * @param val integer value
 * @param num must be >= 0
 * @param den must be >= 1
 */
static void frac_init(AVFrac *f, int64_t val, int64_t num, int64_t den)
{
    num += (den >> 1);
    if (num >= den) {
        val += num / den;
        num = num % den;
    }
    f->val = val;
    f->num = num;
    f->den = den;
}

/**
 * Fractional addition to f: f = f + (incr / f->den).
 *
 * @param f fractional number
 * @param incr increment, can be positive or negative
 */
static void frac_add(AVFrac *f, int64_t incr)
{
    int64_t num, den;

    num = f->num + incr;
    den = f->den;
    if (num < 0) {
        f->val += num / den;
        num = num % den;
        if (num < 0) {
            num += den;
            f->val--;
        }
    } else if (num >= den) {
        f->val += num / den;
        num = num % den;
    }
    f->num = num;
}

/** head of registered input format linked list */
static AVInputFormat *first_iformat = NULL;
/** head of registered output format linked list */
static AVOutputFormat *first_oformat = NULL;

AVInputFormat  *av_iformat_next(AVInputFormat  *f)
{
    if(f) return f->next;
    else  return first_iformat;
}

AVOutputFormat *av_oformat_next(AVOutputFormat *f)
{
    if(f) return f->next;
    else  return first_oformat;
}

void av_register_input_format(AVInputFormat *format)
{
    AVInputFormat **p;
    p = &first_iformat;
    while (*p != NULL) p = &(*p)->next;
    *p = format;
    format->next = NULL;
}

void av_register_output_format(AVOutputFormat *format)
{
    AVOutputFormat **p;
    p = &first_oformat;
    while (*p != NULL) p = &(*p)->next;
    *p = format;
    format->next = NULL;
}

int av_match_ext(const char *filename, const char *extensions)
{
    const char *ext, *p;
    char ext1[32], *q;

    if(!filename)
        return 0;

    ext = strrchr(filename, '.');
    if (ext) {
        ext++;
        p = extensions;
        for(;;) {
            q = ext1;
            while (*p != '\0' && *p != ',' && q-ext1<sizeof(ext1)-1)
                *q++ = *p++;
            *q = '\0';
            if (!av_strcasecmp(ext1, ext))
                return 1;
            if (*p == '\0')
                break;
            p++;
        }
    }
    return 0;
}

static int match_format(const char *name, const char *names)
{
    const char *p;
    int len, namelen;

    if (!name || !names)
        return 0;

    namelen = strlen(name);
    while ((p = strchr(names, ','))) {
        len = FFMAX(p - names, namelen);
        if (!av_strncasecmp(name, names, len))
            return 1;
        names = p+1;
    }
    return !av_strcasecmp(name, names);
}

AVOutputFormat *av_guess_format(const char *short_name, const char *filename,
                                const char *mime_type)
{
    AVOutputFormat *fmt = NULL, *fmt_found;
    int score_max, score;

    /* specific test for image sequences */
#if CONFIG_IMAGE2_MUXER
    if (!short_name && filename &&
        av_filename_number_test(filename) &&
        ff_guess_image2_codec(filename) != AV_CODEC_ID_NONE) {
        return av_guess_format("image2", NULL, NULL);
    }
#endif
    /* Find the proper file type. */
    fmt_found = NULL;
    score_max = 0;
    while ((fmt = av_oformat_next(fmt))) {
        score = 0;
        if (fmt->name && short_name && !av_strcasecmp(fmt->name, short_name))
            score += 100;
        if (fmt->mime_type && mime_type && !strcmp(fmt->mime_type, mime_type))
            score += 10;
        if (filename && fmt->extensions &&
            av_match_ext(filename, fmt->extensions)) {
            score += 5;
        }
        if (score > score_max) {
            score_max = score;
            fmt_found = fmt;
        }
    }
    return fmt_found;
}

enum AVCodecID av_guess_codec(AVOutputFormat *fmt, const char *short_name,
                            const char *filename, const char *mime_type, enum AVMediaType type){
    if(type == AVMEDIA_TYPE_VIDEO){
        enum AVCodecID codec_id= AV_CODEC_ID_NONE;

#if CONFIG_IMAGE2_MUXER
        if(!strcmp(fmt->name, "image2") || !strcmp(fmt->name, "image2pipe")){
            codec_id= ff_guess_image2_codec(filename);
        }
#endif
        if(codec_id == AV_CODEC_ID_NONE)
            codec_id= fmt->video_codec;
        return codec_id;
    }else if(type == AVMEDIA_TYPE_AUDIO)
        return fmt->audio_codec;
    else if (type == AVMEDIA_TYPE_SUBTITLE)
        return fmt->subtitle_codec;
    else
        return AV_CODEC_ID_NONE;
}

AVInputFormat *av_find_input_format(const char *short_name)
{
    AVInputFormat *fmt = NULL;
    while ((fmt = av_iformat_next(fmt))) {
        if (match_format(short_name, fmt->name))
            return fmt;
    }
    return NULL;
}


int av_get_packet(AVIOContext *s, AVPacket *pkt, int size)
{
    int ret= av_new_packet(pkt, size);

    if(ret<0)
        return ret;

    pkt->pos= avio_tell(s);

    ret= avio_read(s, pkt->data, size);
    if(ret<=0)
        av_free_packet(pkt);
    else
        av_shrink_packet(pkt, ret);

    return ret;
}

int av_append_packet(AVIOContext *s, AVPacket *pkt, int size)
{
    int ret;
    int old_size;
    if (!pkt->size)
        return av_get_packet(s, pkt, size);
    old_size = pkt->size;
    ret = av_grow_packet(pkt, size);
    if (ret < 0)
        return ret;
    ret = avio_read(s, pkt->data + old_size, size);
    av_shrink_packet(pkt, old_size + FFMAX(ret, 0));
    return ret;
}


int av_filename_number_test(const char *filename)
{
    char buf[1024];
    return filename && (av_get_frame_filename(buf, sizeof(buf), filename, 1)>=0);
}

AVInputFormat *av_probe_input_format2(AVProbeData *pd, int is_opened, int *score_max)
{
    AVProbeData lpd = *pd;
    AVInputFormat *fmt1 = NULL, *fmt;
    int score, id3 = 0;

    if (lpd.buf_size > 10 && ff_id3v2_match(lpd.buf, ID3v2_DEFAULT_MAGIC)) {
        int id3len = ff_id3v2_tag_len(lpd.buf);
        if (lpd.buf_size > id3len + 16) {
            lpd.buf += id3len;
            lpd.buf_size -= id3len;
        }
        id3 = 1;
    }

    fmt = NULL;
    while ((fmt1 = av_iformat_next(fmt1))) {
        if (!is_opened == !(fmt1->flags & AVFMT_NOFILE))
            continue;
        score = 0;
        if (fmt1->read_probe) {
            score = fmt1->read_probe(&lpd);
        } else if (fmt1->extensions) {
            if (av_match_ext(lpd.filename, fmt1->extensions)) {
                score = 50;
            }
        }
        if (score > *score_max) {
            *score_max = score;
            fmt = fmt1;
        }else if (score == *score_max)
            fmt = NULL;
    }

    /* a hack for files with huge id3v2 tags -- try to guess by file extension. */
    if (!fmt && is_opened && *score_max < AVPROBE_SCORE_MAX/4) {
        while ((fmt = av_iformat_next(fmt)))
            if (fmt->extensions && av_match_ext(lpd.filename, fmt->extensions)) {
                *score_max = AVPROBE_SCORE_MAX/4;
                break;
            }
    }

    if (!fmt && id3 && *score_max < AVPROBE_SCORE_MAX/4-1) {
        while ((fmt = av_iformat_next(fmt)))
            if (fmt->extensions && av_match_ext("mp3", fmt->extensions)) {
                *score_max = AVPROBE_SCORE_MAX/4-1;
                break;
            }
    }

    return fmt;
}

AVInputFormat *av_probe_input_format(AVProbeData *pd, int is_opened){
    int score=0;
    return av_probe_input_format2(pd, is_opened, &score);
}

static int set_codec_from_probe_data(AVFormatContext *s, AVStream *st, AVProbeData *pd, int score)
{
    static const struct {
        const char *name; enum AVCodecID id; enum AVMediaType type;
    } fmt_id_type[] = {
        { "aac"      , AV_CODEC_ID_AAC       , AVMEDIA_TYPE_AUDIO },
        { "ac3"      , AV_CODEC_ID_AC3       , AVMEDIA_TYPE_AUDIO },
        { "dts"      , AV_CODEC_ID_DTS       , AVMEDIA_TYPE_AUDIO },
        { "eac3"     , AV_CODEC_ID_EAC3      , AVMEDIA_TYPE_AUDIO },
        { "h264"     , AV_CODEC_ID_H264      , AVMEDIA_TYPE_VIDEO },
        { "m4v"      , AV_CODEC_ID_MPEG4     , AVMEDIA_TYPE_VIDEO },
        { "mp3"      , AV_CODEC_ID_MP3       , AVMEDIA_TYPE_AUDIO },
        { "mpegvideo", AV_CODEC_ID_MPEG2VIDEO, AVMEDIA_TYPE_VIDEO },
        { 0 }
    };
    AVInputFormat *fmt = av_probe_input_format2(pd, 1, &score);

    if (fmt) {
        int i;
        av_log(s, AV_LOG_DEBUG, "Probe with size=%d, packets=%d detected %s with score=%d\n",
               pd->buf_size, MAX_PROBE_PACKETS - st->probe_packets, fmt->name, score);
        for (i = 0; fmt_id_type[i].name; i++) {
            if (!strcmp(fmt->name, fmt_id_type[i].name)) {
                st->codec->codec_id   = fmt_id_type[i].id;
                st->codec->codec_type = fmt_id_type[i].type;
                break;
            }
        }
    }
    return !!fmt;
}

/************************************************************/
/* input media file */

/** size of probe buffer, for guessing file type from file contents */
#define PROBE_BUF_MIN 2048
#define PROBE_BUF_MAX (1<<20)

int av_probe_input_buffer(AVIOContext *pb, AVInputFormat **fmt,
                          const char *filename, void *logctx,
                          unsigned int offset, unsigned int max_probe_size)
{
    AVProbeData pd = { filename ? filename : "", NULL, -offset };
    unsigned char *buf = NULL;
    int ret = 0, probe_size;

    if (!max_probe_size) {
        max_probe_size = PROBE_BUF_MAX;
    } else if (max_probe_size > PROBE_BUF_MAX) {
        max_probe_size = PROBE_BUF_MAX;
    } else if (max_probe_size < PROBE_BUF_MIN) {
        return AVERROR(EINVAL);
    }

    if (offset >= max_probe_size) {
        return AVERROR(EINVAL);
    }

    for(probe_size= PROBE_BUF_MIN; probe_size<=max_probe_size && !*fmt;
        probe_size = FFMIN(probe_size<<1, FFMAX(max_probe_size, probe_size+1))) {
        int score = probe_size < max_probe_size ? AVPROBE_SCORE_MAX/4 : 0;
        int buf_offset = (probe_size == PROBE_BUF_MIN) ? 0 : probe_size>>1;

        if (probe_size < offset) {
            continue;
        }

        /* read probe data */
        buf = av_realloc(buf, probe_size + AVPROBE_PADDING_SIZE);
        if ((ret = avio_read(pb, buf + buf_offset, probe_size - buf_offset)) < 0) {
            /* fail if error was not end of file, otherwise, lower score */
            if (ret != AVERROR_EOF) {
                av_free(buf);
                return ret;
            }
            score = 0;
            ret = 0;            /* error was end of file, nothing read */
        }
        pd.buf_size += ret;
        pd.buf = &buf[offset];

        memset(pd.buf + pd.buf_size, 0, AVPROBE_PADDING_SIZE);

        /* guess file format */
        *fmt = av_probe_input_format2(&pd, 1, &score);
        if(*fmt){
            if(score <= AVPROBE_SCORE_MAX/4){ //this can only be true in the last iteration
                av_log(logctx, AV_LOG_WARNING, "Format detected only with low score of %d, misdetection possible!\n", score);
            }else
                av_log(logctx, AV_LOG_DEBUG, "Probed with size=%d and score=%d\n", probe_size, score);
        }
    }

    if (!*fmt) {
        av_free(buf);
        return AVERROR_INVALIDDATA;
    }

    /* rewind. reuse probe buffer to avoid seeking */
    if ((ret = ffio_rewind_with_probe_data(pb, buf, pd.buf_size)) < 0)
        av_free(buf);

    return ret;
}

/* open input file and probe the format if necessary */
static int init_input(AVFormatContext *s, const char *filename, AVDictionary **options)
{
    int ret;
    AVProbeData pd = {filename, NULL, 0};

    if (s->pb) {
        s->flags |= AVFMT_FLAG_CUSTOM_IO;
        if (!s->iformat)
            return av_probe_input_buffer(s->pb, &s->iformat, filename, s, 0, s->probesize);
        else if (s->iformat->flags & AVFMT_NOFILE)
            return AVERROR(EINVAL);
        return 0;
    }

    if ( (s->iformat && s->iformat->flags & AVFMT_NOFILE) ||
        (!s->iformat && (s->iformat = av_probe_input_format(&pd, 0))))
        return 0;

    if ((ret = avio_open2(&s->pb, filename, AVIO_FLAG_READ,
                          &s->interrupt_callback, options)) < 0)
        return ret;
    if (s->iformat)
        return 0;
    return av_probe_input_buffer(s->pb, &s->iformat, filename, s, 0, s->probesize);
}

static AVPacket *add_to_pktbuf(AVPacketList **packet_buffer, AVPacket *pkt,
                               AVPacketList **plast_pktl){
    AVPacketList *pktl = av_mallocz(sizeof(AVPacketList));
    if (!pktl)
        return NULL;

    if (*packet_buffer)
        (*plast_pktl)->next = pktl;
    else
        *packet_buffer = pktl;

    /* add the packet in the buffered packet list */
    *plast_pktl = pktl;
    pktl->pkt= *pkt;
    return &pktl->pkt;
}

static void queue_attached_pictures(AVFormatContext *s)
{
    int i;
    for (i = 0; i < s->nb_streams; i++)
        if (s->streams[i]->disposition & AV_DISPOSITION_ATTACHED_PIC &&
            s->streams[i]->discard < AVDISCARD_ALL) {
            AVPacket copy = s->streams[i]->attached_pic;
            copy.destruct = NULL;
            add_to_pktbuf(&s->raw_packet_buffer, &copy, &s->raw_packet_buffer_end);
        }
}

int avformat_open_input(AVFormatContext **ps, const char *filename, AVInputFormat *fmt, AVDictionary **options)
{
    AVFormatContext *s = *ps;
    int ret = 0;
    AVDictionary *tmp = NULL;
    ID3v2ExtraMeta *id3v2_extra_meta = NULL;

    if (!s && !(s = avformat_alloc_context()))
        return AVERROR(ENOMEM);
    if (fmt)
        s->iformat = fmt;

    if (options)
        av_dict_copy(&tmp, *options, 0);

    if ((ret = av_opt_set_dict(s, &tmp)) < 0)
        goto fail;

    if ((ret = init_input(s, filename, &tmp)) < 0)
        goto fail;

    /* check filename in case an image number is expected */
    if (s->iformat->flags & AVFMT_NEEDNUMBER) {
        if (!av_filename_number_test(filename)) {
            ret = AVERROR(EINVAL);
            goto fail;
        }
    }

    s->duration = s->start_time = AV_NOPTS_VALUE;
    av_strlcpy(s->filename, filename ? filename : "", sizeof(s->filename));

    /* allocate private data */
    if (s->iformat->priv_data_size > 0) {
        if (!(s->priv_data = av_mallocz(s->iformat->priv_data_size))) {
            ret = AVERROR(ENOMEM);
            goto fail;
        }
        if (s->iformat->priv_class) {
            *(const AVClass**)s->priv_data = s->iformat->priv_class;
            av_opt_set_defaults(s->priv_data);
            if ((ret = av_opt_set_dict(s->priv_data, &tmp)) < 0)
                goto fail;
        }
    }

    /* e.g. AVFMT_NOFILE formats will not have a AVIOContext */
    if (s->pb)
        ff_id3v2_read(s, ID3v2_DEFAULT_MAGIC, &id3v2_extra_meta);

    if (s->iformat->read_header)
        if ((ret = s->iformat->read_header(s)) < 0)
            goto fail;

    if (id3v2_extra_meta &&
        (ret = ff_id3v2_parse_apic(s, &id3v2_extra_meta)) < 0)
        goto fail;
    ff_id3v2_free_extra_meta(&id3v2_extra_meta);

    queue_attached_pictures(s);

    if (s->pb && !s->data_offset)
        s->data_offset = avio_tell(s->pb);

    s->raw_packet_buffer_remaining_size = RAW_PACKET_BUFFER_SIZE;

    if (options) {
        av_dict_free(options);
        *options = tmp;
    }
    *ps = s;
    return 0;

fail:
    ff_id3v2_free_extra_meta(&id3v2_extra_meta);
    av_dict_free(&tmp);
    if (s->pb && !(s->flags & AVFMT_FLAG_CUSTOM_IO))
        avio_close(s->pb);
    avformat_free_context(s);
    *ps = NULL;
    return ret;
}

/*******************************************************/

static void probe_codec(AVFormatContext *s, AVStream *st, const AVPacket *pkt)
{
    if(st->codec->codec_id == AV_CODEC_ID_PROBE){
        AVProbeData *pd = &st->probe_data;
        av_log(s, AV_LOG_DEBUG, "probing stream %d\n", st->index);
        --st->probe_packets;

        if (pkt) {
            pd->buf = av_realloc(pd->buf, pd->buf_size+pkt->size+AVPROBE_PADDING_SIZE);
            memcpy(pd->buf+pd->buf_size, pkt->data, pkt->size);
            pd->buf_size += pkt->size;
            memset(pd->buf+pd->buf_size, 0, AVPROBE_PADDING_SIZE);
        } else {
            st->probe_packets = 0;
        }

        if (!st->probe_packets ||
            av_log2(pd->buf_size) != av_log2(pd->buf_size - pkt->size)) {
            set_codec_from_probe_data(s, st, pd, st->probe_packets > 0 ? AVPROBE_SCORE_MAX/4 : 0);
            if(st->codec->codec_id != AV_CODEC_ID_PROBE){
                pd->buf_size=0;
                av_freep(&pd->buf);
                av_log(s, AV_LOG_DEBUG, "probed stream %d\n", st->index);
            }
        }
    }
}

int ff_read_packet(AVFormatContext *s, AVPacket *pkt)
{
    int ret, i;
    AVStream *st;

    for(;;){
        AVPacketList *pktl = s->raw_packet_buffer;

        if (pktl) {
            *pkt = pktl->pkt;
            st = s->streams[pkt->stream_index];
            if (st->codec->codec_id != AV_CODEC_ID_PROBE || !st->probe_packets ||
                s->raw_packet_buffer_remaining_size < pkt->size) {
                AVProbeData *pd;
                if (st->probe_packets) {
                    probe_codec(s, st, NULL);
                }
                pd = &st->probe_data;
                av_freep(&pd->buf);
                pd->buf_size = 0;
                s->raw_packet_buffer = pktl->next;
                s->raw_packet_buffer_remaining_size += pkt->size;
                av_free(pktl);
                return 0;
            }
        }

        av_init_packet(pkt);
        ret= s->iformat->read_packet(s, pkt);
        if (ret < 0) {
            if (!pktl || ret == AVERROR(EAGAIN))
                return ret;
            for (i = 0; i < s->nb_streams; i++) {
                st = s->streams[i];
                if (st->probe_packets) {
                    probe_codec(s, st, NULL);
                }
            }
            continue;
        }

        if ((s->flags & AVFMT_FLAG_DISCARD_CORRUPT) &&
            (pkt->flags & AV_PKT_FLAG_CORRUPT)) {
            av_log(s, AV_LOG_WARNING,
                   "Dropped corrupted packet (stream = %d)\n",
                   pkt->stream_index);
            av_free_packet(pkt);
            continue;
        }

        st= s->streams[pkt->stream_index];

        switch(st->codec->codec_type){
        case AVMEDIA_TYPE_VIDEO:
            if(s->video_codec_id)   st->codec->codec_id= s->video_codec_id;
            break;
        case AVMEDIA_TYPE_AUDIO:
            if(s->audio_codec_id)   st->codec->codec_id= s->audio_codec_id;
            break;
        case AVMEDIA_TYPE_SUBTITLE:
            if(s->subtitle_codec_id)st->codec->codec_id= s->subtitle_codec_id;
            break;
        }

        if(!pktl && (st->codec->codec_id != AV_CODEC_ID_PROBE ||
                     !st->probe_packets))
            return ret;

        add_to_pktbuf(&s->raw_packet_buffer, pkt, &s->raw_packet_buffer_end);
        s->raw_packet_buffer_remaining_size -= pkt->size;

        probe_codec(s, st, pkt);
    }
}

#if FF_API_READ_PACKET
int av_read_packet(AVFormatContext *s, AVPacket *pkt)
{
    return ff_read_packet(s, pkt);
}
#endif


/**********************************************************/

/**
 * Get the number of samples of an audio frame. Return -1 on error.
 */
static int get_audio_frame_size(AVCodecContext *enc, int size, int mux)
{
    int frame_size;

    /* give frame_size priority if demuxing */
    if (!mux && enc->frame_size > 1)
        return enc->frame_size;

    if ((frame_size = av_get_audio_frame_duration(enc, size)) > 0)
        return frame_size;

    /* fallback to using frame_size if muxing */
    if (enc->frame_size > 1)
        return enc->frame_size;

    return -1;
}


/**
 * Return the frame duration in seconds. Return 0 if not available.
 */
static void compute_frame_duration(int *pnum, int *pden, AVStream *st,
                                   AVCodecParserContext *pc, AVPacket *pkt)
{
    int frame_size;

    *pnum = 0;
    *pden = 0;
    switch(st->codec->codec_type) {
    case AVMEDIA_TYPE_VIDEO:
        if (st->avg_frame_rate.num) {
            *pnum = st->avg_frame_rate.den;
            *pden = st->avg_frame_rate.num;
        } else if(st->time_base.num*1000LL > st->time_base.den) {
            *pnum = st->time_base.num;
            *pden = st->time_base.den;
        }else if(st->codec->time_base.num*1000LL > st->codec->time_base.den){
            *pnum = st->codec->time_base.num;
            *pden = st->codec->time_base.den;
            if (pc && pc->repeat_pict) {
                *pnum = (*pnum) * (1 + pc->repeat_pict);
            }
            //If this codec can be interlaced or progressive then we need a parser to compute duration of a packet
            //Thus if we have no parser in such case leave duration undefined.
            if(st->codec->ticks_per_frame>1 && !pc){
                *pnum = *pden = 0;
            }
        }
        break;
    case AVMEDIA_TYPE_AUDIO:
        frame_size = get_audio_frame_size(st->codec, pkt->size, 0);
        if (frame_size <= 0 || st->codec->sample_rate <= 0)
            break;
        *pnum = frame_size;
        *pden = st->codec->sample_rate;
        break;
    default:
        break;
    }
}

static int is_intra_only(AVCodecContext *enc){
    if(enc->codec_type == AVMEDIA_TYPE_AUDIO){
        return 1;
    }else if(enc->codec_type == AVMEDIA_TYPE_VIDEO){
        switch(enc->codec_id){
        case AV_CODEC_ID_MJPEG:
        case AV_CODEC_ID_MJPEGB:
        case AV_CODEC_ID_LJPEG:
        case AV_CODEC_ID_PRORES:
        case AV_CODEC_ID_RAWVIDEO:
        case AV_CODEC_ID_DVVIDEO:
        case AV_CODEC_ID_HUFFYUV:
        case AV_CODEC_ID_FFVHUFF:
        case AV_CODEC_ID_ASV1:
        case AV_CODEC_ID_ASV2:
        case AV_CODEC_ID_VCR1:
        case AV_CODEC_ID_DNXHD:
        case AV_CODEC_ID_JPEG2000:
        case AV_CODEC_ID_MDEC:
            return 1;
        default: break;
        }
    }
    return 0;
}

static void update_initial_timestamps(AVFormatContext *s, int stream_index,
                                      int64_t dts, int64_t pts)
{
    AVStream *st= s->streams[stream_index];
    AVPacketList *pktl= s->packet_buffer;

    if(st->first_dts != AV_NOPTS_VALUE || dts == AV_NOPTS_VALUE || st->cur_dts == AV_NOPTS_VALUE)
        return;

    st->first_dts= dts - st->cur_dts;
    st->cur_dts= dts;

    for(; pktl; pktl= pktl->next){
        if(pktl->pkt.stream_index != stream_index)
            continue;
        //FIXME think more about this check
        if(pktl->pkt.pts != AV_NOPTS_VALUE && pktl->pkt.pts == pktl->pkt.dts)
            pktl->pkt.pts += st->first_dts;

        if(pktl->pkt.dts != AV_NOPTS_VALUE)
            pktl->pkt.dts += st->first_dts;

        if(st->start_time == AV_NOPTS_VALUE && pktl->pkt.pts != AV_NOPTS_VALUE)
            st->start_time= pktl->pkt.pts;
    }
    if (st->start_time == AV_NOPTS_VALUE)
        st->start_time = pts;
}

static void update_initial_durations(AVFormatContext *s, AVStream *st,
                                     int stream_index, int duration)
{
    AVPacketList *pktl= s->packet_buffer;
    int64_t cur_dts= 0;

    if(st->first_dts != AV_NOPTS_VALUE){
        cur_dts= st->first_dts;
        for(; pktl; pktl= pktl->next){
            if(pktl->pkt.stream_index == stream_index){
                if(pktl->pkt.pts != pktl->pkt.dts || pktl->pkt.dts != AV_NOPTS_VALUE || pktl->pkt.duration)
                    break;
                cur_dts -= duration;
            }
        }
        pktl= s->packet_buffer;
        st->first_dts = cur_dts;
    }else if(st->cur_dts)
        return;

    for(; pktl; pktl= pktl->next){
        if(pktl->pkt.stream_index != stream_index)
            continue;
        if(pktl->pkt.pts == pktl->pkt.dts && pktl->pkt.dts == AV_NOPTS_VALUE
           && !pktl->pkt.duration){
            pktl->pkt.dts= cur_dts;
            if(!st->codec->has_b_frames)
                pktl->pkt.pts= cur_dts;
            cur_dts += duration;
            if (st->codec->codec_type != AVMEDIA_TYPE_AUDIO)
                pktl->pkt.duration = duration;
        }else
            break;
    }
    if(st->first_dts == AV_NOPTS_VALUE)
        st->cur_dts= cur_dts;
}

static void compute_pkt_fields(AVFormatContext *s, AVStream *st,
                               AVCodecParserContext *pc, AVPacket *pkt)
{
    int num, den, presentation_delayed, delay, i;
    int64_t offset;

    if (s->flags & AVFMT_FLAG_NOFILLIN)
        return;

    if((s->flags & AVFMT_FLAG_IGNDTS) && pkt->pts != AV_NOPTS_VALUE)
        pkt->dts= AV_NOPTS_VALUE;

    /* do we have a video B-frame ? */
    delay= st->codec->has_b_frames;
    presentation_delayed = 0;

    /* XXX: need has_b_frame, but cannot get it if the codec is
        not initialized */
    if (delay &&
        pc && pc->pict_type != AV_PICTURE_TYPE_B)
        presentation_delayed = 1;

    if(pkt->pts != AV_NOPTS_VALUE && pkt->dts != AV_NOPTS_VALUE && pkt->dts > pkt->pts && st->pts_wrap_bits<63
       /*&& pkt->dts-(1LL<<st->pts_wrap_bits) < pkt->pts*/){
        pkt->dts -= 1LL<<st->pts_wrap_bits;
    }

    // some mpeg2 in mpeg-ps lack dts (issue171 / input_file.mpg)
    // we take the conservative approach and discard both
    // Note, if this is misbehaving for a H.264 file then possibly presentation_delayed is not set correctly.
    if(delay==1 && pkt->dts == pkt->pts && pkt->dts != AV_NOPTS_VALUE && presentation_delayed){
        av_log(s, AV_LOG_DEBUG, "invalid dts/pts combination\n");
        pkt->dts= pkt->pts= AV_NOPTS_VALUE;
    }

    if (pkt->duration == 0 && st->codec->codec_type != AVMEDIA_TYPE_AUDIO) {
        compute_frame_duration(&num, &den, st, pc, pkt);
        if (den && num) {
            pkt->duration = av_rescale_rnd(1, num * (int64_t)st->time_base.den, den * (int64_t)st->time_base.num, AV_ROUND_DOWN);

            if(pkt->duration != 0 && s->packet_buffer)
                update_initial_durations(s, st, pkt->stream_index, pkt->duration);
        }
    }

    /* correct timestamps with byte offset if demuxers only have timestamps
       on packet boundaries */
    if(pc && st->need_parsing == AVSTREAM_PARSE_TIMESTAMPS && pkt->size){
        /* this will estimate bitrate based on this frame's duration and size */
        offset = av_rescale(pc->offset, pkt->duration, pkt->size);
        if(pkt->pts != AV_NOPTS_VALUE)
            pkt->pts += offset;
        if(pkt->dts != AV_NOPTS_VALUE)
            pkt->dts += offset;
    }

    if (pc && pc->dts_sync_point >= 0) {
        // we have synchronization info from the parser
        int64_t den = st->codec->time_base.den * (int64_t) st->time_base.num;
        if (den > 0) {
            int64_t num = st->codec->time_base.num * (int64_t) st->time_base.den;
            if (pkt->dts != AV_NOPTS_VALUE) {
                // got DTS from the stream, update reference timestamp
                st->reference_dts = pkt->dts - pc->dts_ref_dts_delta * num / den;
                pkt->pts = pkt->dts + pc->pts_dts_delta * num / den;
            } else if (st->reference_dts != AV_NOPTS_VALUE) {
                // compute DTS based on reference timestamp
                pkt->dts = st->reference_dts + pc->dts_ref_dts_delta * num / den;
                pkt->pts = pkt->dts + pc->pts_dts_delta * num / den;
            }
            if (pc->dts_sync_point > 0)
                st->reference_dts = pkt->dts; // new reference
        }
    }

    /* This may be redundant, but it should not hurt. */
    if(pkt->dts != AV_NOPTS_VALUE && pkt->pts != AV_NOPTS_VALUE && pkt->pts > pkt->dts)
        presentation_delayed = 1;

//    av_log(NULL, AV_LOG_DEBUG, "IN delayed:%d pts:%"PRId64", dts:%"PRId64" cur_dts:%"PRId64" st:%d pc:%p\n", presentation_delayed, pkt->pts, pkt->dts, st->cur_dts, pkt->stream_index, pc);
    /* interpolate PTS and DTS if they are not present */
    //We skip H264 currently because delay and has_b_frames are not reliably set
    if((delay==0 || (delay==1 && pc)) && st->codec->codec_id != AV_CODEC_ID_H264){
        if (presentation_delayed) {
            /* DTS = decompression timestamp */
            /* PTS = presentation timestamp */
            if (pkt->dts == AV_NOPTS_VALUE)
                pkt->dts = st->last_IP_pts;
            update_initial_timestamps(s, pkt->stream_index, pkt->dts, pkt->pts);
            if (pkt->dts == AV_NOPTS_VALUE)
                pkt->dts = st->cur_dts;

            /* this is tricky: the dts must be incremented by the duration
            of the frame we are displaying, i.e. the last I- or P-frame */
            if (st->last_IP_duration == 0)
                st->last_IP_duration = pkt->duration;
            if(pkt->dts != AV_NOPTS_VALUE)
                st->cur_dts = pkt->dts + st->last_IP_duration;
            st->last_IP_duration  = pkt->duration;
            st->last_IP_pts= pkt->pts;
            /* cannot compute PTS if not present (we can compute it only
            by knowing the future */
        } else if (pkt->pts != AV_NOPTS_VALUE ||
                   pkt->dts != AV_NOPTS_VALUE ||
                   pkt->duration              ||
                   st->codec->codec_type == AVMEDIA_TYPE_AUDIO) {
            int duration = pkt->duration;
            if (!duration && st->codec->codec_type == AVMEDIA_TYPE_AUDIO) {
                compute_frame_duration(&num, &den, st, pc, pkt);
                if (den && num) {
                    duration = av_rescale_rnd(1, num * (int64_t)st->time_base.den,
                                                 den * (int64_t)st->time_base.num,
                                                 AV_ROUND_DOWN);
                    if (duration != 0 && s->packet_buffer) {
                        update_initial_durations(s, st, pkt->stream_index,
                                                 duration);