ffprobe.c

/*
 * Copyright (c) 2007-2010 Stefano Sabatini
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg 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.
 *
 * FFmpeg 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 FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

/**
 * @file
 * simple media prober based on the FFmpeg libraries
 */

#include "config.h"
#include "version.h"

#include <string.h>

#include "libavformat/avformat.h"
#include "libavcodec/avcodec.h"
#include "libavutil/avassert.h"
#include "libavutil/avstring.h"
#include "libavutil/bprint.h"
#include "libavutil/opt.h"
#include "libavutil/pixdesc.h"
#include "libavutil/dict.h"
#include "libavutil/libm.h"
#include "libavutil/parseutils.h"
#include "libavutil/timecode.h"
#include "libavutil/timestamp.h"
#include "libavdevice/avdevice.h"
#include "libswscale/swscale.h"
#include "libswresample/swresample.h"
#include "libpostproc/postprocess.h"
#include "cmdutils.h"

const char program_name[] = "ffprobe";
const int program_birth_year = 2007;

static int do_bitexact = 0;
static int do_count_frames = 0;
static int do_count_packets = 0;
static int do_read_frames  = 0;
static int do_read_packets = 0;
static int do_show_chapters = 0;
static int do_show_error   = 0;
static int do_show_format  = 0;
static int do_show_frames  = 0;
static int do_show_packets = 0;
static int do_show_programs = 0;
static int do_show_streams = 0;
static int do_show_stream_disposition = 0;
static int do_show_data    = 0;
static int do_show_program_version  = 0;
static int do_show_library_versions = 0;

static int show_value_unit              = 0;
static int use_value_prefix             = 0;
static int use_byte_value_binary_prefix = 0;
static int use_value_sexagesimal_format = 0;
static int show_private_data            = 1;

static char *print_format;
static char *stream_specifier;

typedef struct {
    int id;             ///< identifier
    int64_t start, end; ///< start, end in second/AV_TIME_BASE units
    int has_start, has_end;
    int start_is_offset, end_is_offset;
    int duration_frames;
} ReadInterval;

static ReadInterval *read_intervals;
static int read_intervals_nb = 0;

/* section structure definition */

#define SECTION_MAX_NB_CHILDREN 10

struct section {
    int id;             ///< unique id identifying a section
    const char *name;

#define SECTION_FLAG_IS_WRAPPER      1 ///< the section only contains other sections, but has no data at its own level
#define SECTION_FLAG_IS_ARRAY        2 ///< the section contains an array of elements of the same type
#define SECTION_FLAG_HAS_VARIABLE_FIELDS 4 ///< the section may contain a variable number of fields with variable keys.
                                           ///  For these sections the element_name field is mandatory.
    int flags;
    int children_ids[SECTION_MAX_NB_CHILDREN+1]; ///< list of children section IDS, terminated by -1
    const char *element_name; ///< name of the contained element, if provided
    const char *unique_name;  ///< unique section name, in case the name is ambiguous
    AVDictionary *entries_to_show;
    int show_all_entries;
};

typedef enum {
    SECTION_ID_NONE = -1,
    SECTION_ID_CHAPTER,
    SECTION_ID_CHAPTER_TAGS,
    SECTION_ID_CHAPTERS,
    SECTION_ID_ERROR,
    SECTION_ID_FORMAT,
    SECTION_ID_FORMAT_TAGS,
    SECTION_ID_FRAME,
    SECTION_ID_FRAMES,
    SECTION_ID_FRAME_TAGS,
    SECTION_ID_LIBRARY_VERSION,
    SECTION_ID_LIBRARY_VERSIONS,
    SECTION_ID_PACKET,
    SECTION_ID_PACKETS,
    SECTION_ID_PACKETS_AND_FRAMES,
    SECTION_ID_PROGRAM_STREAM_DISPOSITION,
    SECTION_ID_PROGRAM_STREAM_TAGS,
    SECTION_ID_PROGRAM,
    SECTION_ID_PROGRAM_STREAMS,
    SECTION_ID_PROGRAM_STREAM,
    SECTION_ID_PROGRAM_TAGS,
    SECTION_ID_PROGRAM_VERSION,
    SECTION_ID_PROGRAMS,
    SECTION_ID_ROOT,
    SECTION_ID_STREAM,
    SECTION_ID_STREAM_DISPOSITION,
    SECTION_ID_STREAMS,
    SECTION_ID_STREAM_TAGS,
    SECTION_ID_SUBTITLE,
} SectionID;

static struct section sections[] = {
    [SECTION_ID_CHAPTERS] =           { SECTION_ID_CHAPTERS, "chapters", SECTION_FLAG_IS_ARRAY, { SECTION_ID_CHAPTER, -1 } },
    [SECTION_ID_CHAPTER] =            { SECTION_ID_CHAPTER, "chapter", 0, { SECTION_ID_CHAPTER_TAGS, -1 } },
    [SECTION_ID_CHAPTER_TAGS] =       { SECTION_ID_CHAPTER_TAGS, "tags", SECTION_FLAG_HAS_VARIABLE_FIELDS, { -1 }, .element_name = "tag", .unique_name = "chapter_tags" },
    [SECTION_ID_ERROR] =              { SECTION_ID_ERROR, "error", 0, { -1 } },
    [SECTION_ID_FORMAT] =             { SECTION_ID_FORMAT, "format", 0, { SECTION_ID_FORMAT_TAGS, -1 } },
    [SECTION_ID_FORMAT_TAGS] =        { SECTION_ID_FORMAT_TAGS, "tags", SECTION_FLAG_HAS_VARIABLE_FIELDS, { -1 }, .element_name = "tag", .unique_name = "format_tags" },
    [SECTION_ID_FRAMES] =             { SECTION_ID_FRAMES, "frames", SECTION_FLAG_IS_ARRAY, { SECTION_ID_FRAME, SECTION_ID_SUBTITLE, -1 } },
    [SECTION_ID_FRAME] =              { SECTION_ID_FRAME, "frame", 0, { SECTION_ID_FRAME_TAGS, -1 } },
    [SECTION_ID_FRAME_TAGS] =         { SECTION_ID_FRAME_TAGS, "tags", SECTION_FLAG_HAS_VARIABLE_FIELDS, { -1 }, .element_name = "tag", .unique_name = "frame_tags" },
    [SECTION_ID_LIBRARY_VERSIONS] =   { SECTION_ID_LIBRARY_VERSIONS, "library_versions", SECTION_FLAG_IS_ARRAY, { SECTION_ID_LIBRARY_VERSION, -1 } },
    [SECTION_ID_LIBRARY_VERSION] =    { SECTION_ID_LIBRARY_VERSION, "library_version", 0, { -1 } },
    [SECTION_ID_PACKETS] =            { SECTION_ID_PACKETS, "packets", SECTION_FLAG_IS_ARRAY, { SECTION_ID_PACKET, -1} },
    [SECTION_ID_PACKETS_AND_FRAMES] = { SECTION_ID_PACKETS_AND_FRAMES, "packets_and_frames", SECTION_FLAG_IS_ARRAY, { SECTION_ID_PACKET, -1} },
    [SECTION_ID_PACKET] =             { SECTION_ID_PACKET, "packet", 0, { -1 } },
    [SECTION_ID_PROGRAM_STREAM_DISPOSITION] = { SECTION_ID_PROGRAM_STREAM_DISPOSITION, "disposition", 0, { -1 }, .unique_name = "program_stream_disposition" },
    [SECTION_ID_PROGRAM_STREAM_TAGS] =        { SECTION_ID_PROGRAM_STREAM_TAGS, "tags", SECTION_FLAG_HAS_VARIABLE_FIELDS, { -1 }, .element_name = "tag", .unique_name = "program_stream_tags" },
    [SECTION_ID_PROGRAM] =                    { SECTION_ID_PROGRAM, "program", 0, { SECTION_ID_PROGRAM_TAGS, SECTION_ID_PROGRAM_STREAMS, -1 } },
    [SECTION_ID_PROGRAM_STREAMS] =            { SECTION_ID_PROGRAM_STREAMS, "streams", SECTION_FLAG_IS_ARRAY, { SECTION_ID_PROGRAM_STREAM, -1 }, .unique_name = "program_streams" },
    [SECTION_ID_PROGRAM_STREAM] =             { SECTION_ID_PROGRAM_STREAM, "stream", 0, { SECTION_ID_PROGRAM_STREAM_DISPOSITION, SECTION_ID_PROGRAM_STREAM_TAGS, -1 }, .unique_name = "program_stream" },
    [SECTION_ID_PROGRAM_TAGS] =               { SECTION_ID_PROGRAM_TAGS, "tags", SECTION_FLAG_HAS_VARIABLE_FIELDS, { -1 }, .element_name = "tag", .unique_name = "program_tags" },
    [SECTION_ID_PROGRAM_VERSION] =    { SECTION_ID_PROGRAM_VERSION, "program_version", 0, { -1 } },
    [SECTION_ID_PROGRAMS] =                   { SECTION_ID_PROGRAMS, "programs", SECTION_FLAG_IS_ARRAY, { SECTION_ID_PROGRAM, -1 } },
    [SECTION_ID_ROOT] =               { SECTION_ID_ROOT, "root", SECTION_FLAG_IS_WRAPPER,
                                        { SECTION_ID_CHAPTERS, SECTION_ID_FORMAT, SECTION_ID_FRAMES, SECTION_ID_PROGRAMS, SECTION_ID_STREAMS,
                                          SECTION_ID_PACKETS, SECTION_ID_ERROR, SECTION_ID_PROGRAM_VERSION, SECTION_ID_LIBRARY_VERSIONS, -1} },
    [SECTION_ID_STREAMS] =            { SECTION_ID_STREAMS, "streams", SECTION_FLAG_IS_ARRAY, { SECTION_ID_STREAM, -1 } },
    [SECTION_ID_STREAM] =             { SECTION_ID_STREAM, "stream", 0, { SECTION_ID_STREAM_DISPOSITION, SECTION_ID_STREAM_TAGS, -1 } },
    [SECTION_ID_STREAM_DISPOSITION] = { SECTION_ID_STREAM_DISPOSITION, "disposition", 0, { -1 }, .unique_name = "stream_disposition" },
    [SECTION_ID_STREAM_TAGS] =        { SECTION_ID_STREAM_TAGS, "tags", SECTION_FLAG_HAS_VARIABLE_FIELDS, { -1 }, .element_name = "tag", .unique_name = "stream_tags" },
    [SECTION_ID_SUBTITLE] =           { SECTION_ID_SUBTITLE, "subtitle", 0, { -1 } },
};

static const OptionDef *options;

/* FFprobe context */
static const char *input_filename;
static AVInputFormat *iformat = NULL;

static const char *const binary_unit_prefixes [] = { "", "Ki", "Mi", "Gi", "Ti", "Pi" };
static const char *const decimal_unit_prefixes[] = { "", "K" , "M" , "G" , "T" , "P"  };

static const char unit_second_str[]         = "s"    ;
static const char unit_hertz_str[]          = "Hz"   ;
static const char unit_byte_str[]           = "byte" ;
static const char unit_bit_per_second_str[] = "bit/s";

static uint64_t *nb_streams_packets;
static uint64_t *nb_streams_frames;
static int *selected_streams;

static void ffprobe_cleanup(int ret)
{
    int i;
    for (i = 0; i < FF_ARRAY_ELEMS(sections); i++)
        av_dict_free(&(sections[i].entries_to_show));
}

struct unit_value {
    union { double d; long long int i; } val;
    const char *unit;
};

static char *value_string(char *buf, int buf_size, struct unit_value uv)
{
    double vald;
    long long int vali;
    int show_float = 0;

    if (uv.unit == unit_second_str) {
        vald = uv.val.d;
        show_float = 1;
    } else {
        vald = vali = uv.val.i;
    }

    if (uv.unit == unit_second_str && use_value_sexagesimal_format) {
        double secs;
        int hours, mins;
        secs  = vald;
        mins  = (int)secs / 60;
        secs  = secs - mins * 60;
        hours = mins / 60;
        mins %= 60;
        snprintf(buf, buf_size, "%d:%02d:%09.6f", hours, mins, secs);
    } else {
        const char *prefix_string = "";

        if (use_value_prefix && vald > 1) {
            long long int index;

            if (uv.unit == unit_byte_str && use_byte_value_binary_prefix) {
                index = (long long int) (log2(vald)) / 10;
                index = av_clip(index, 0, FF_ARRAY_ELEMS(binary_unit_prefixes) - 1);
                vald /= exp2(index * 10);
                prefix_string = binary_unit_prefixes[index];
            } else {
                index = (long long int) (log10(vald)) / 3;
                index = av_clip(index, 0, FF_ARRAY_ELEMS(decimal_unit_prefixes) - 1);
                vald /= pow(10, index * 3);
                prefix_string = decimal_unit_prefixes[index];
            }
        }

        if (show_float || (use_value_prefix && vald != (long long int)vald))
            snprintf(buf, buf_size, "%f", vald);
        else
            snprintf(buf, buf_size, "%lld", vali);
        av_strlcatf(buf, buf_size, "%s%s%s", *prefix_string || show_value_unit ? " " : "",
                 prefix_string, show_value_unit ? uv.unit : "");
    }

    return buf;
}

/* WRITERS API */

typedef struct WriterContext WriterContext;

#define WRITER_FLAG_DISPLAY_OPTIONAL_FIELDS 1
#define WRITER_FLAG_PUT_PACKETS_AND_FRAMES_IN_SAME_CHAPTER 2

typedef enum {
    WRITER_STRING_VALIDATION_FAIL,
    WRITER_STRING_VALIDATION_REPLACE,
    WRITER_STRING_VALIDATION_IGNORE,
    WRITER_STRING_VALIDATION_NB
} StringValidation;

typedef struct Writer {
    const AVClass *priv_class;      ///< private class of the writer, if any
    int priv_size;                  ///< private size for the writer context
    const char *name;

    int  (*init)  (WriterContext *wctx);
    void (*uninit)(WriterContext *wctx);

    void (*print_section_header)(WriterContext *wctx);
    void (*print_section_footer)(WriterContext *wctx);
    void (*print_integer)       (WriterContext *wctx, const char *, long long int);
    void (*print_rational)      (WriterContext *wctx, AVRational *q, char *sep);
    void (*print_string)        (WriterContext *wctx, const char *, const char *);
    int flags;                  ///< a combination or WRITER_FLAG_*
} Writer;

#define SECTION_MAX_NB_LEVELS 10

struct WriterContext {
    const AVClass *class;           ///< class of the writer
    const Writer *writer;           ///< the Writer of which this is an instance
    char *name;                     ///< name of this writer instance
    void *priv;                     ///< private data for use by the filter

    const struct section *sections; ///< array containing all sections
    int nb_sections;                ///< number of sections

    int level;                      ///< current level, starting from 0

    /** number of the item printed in the given section, starting from 0 */
    unsigned int nb_item[SECTION_MAX_NB_LEVELS];

    /** section per each level */
    const struct section *section[SECTION_MAX_NB_LEVELS];
    AVBPrint section_pbuf[SECTION_MAX_NB_LEVELS]; ///< generic print buffer dedicated to each section,
                                                  ///  used by various writers

    unsigned int nb_section_packet; ///< number of the packet section in case we are in "packets_and_frames" section
    unsigned int nb_section_frame;  ///< number of the frame  section in case we are in "packets_and_frames" section
    unsigned int nb_section_packet_frame; ///< nb_section_packet or nb_section_frame according if is_packets_and_frames

    StringValidation string_validation;
    char *string_validation_replacement;
    unsigned int string_validation_utf8_flags;
};

static const char *writer_get_name(void *p)
{
    WriterContext *wctx = p;
    return wctx->writer->name;
}

#define OFFSET(x) offsetof(WriterContext, x)

static const AVOption writer_options[] = {
    { "string_validation", "set string validation mode",
      OFFSET(string_validation), AV_OPT_TYPE_INT, {.i64=WRITER_STRING_VALIDATION_REPLACE}, 0, WRITER_STRING_VALIDATION_NB-1, .unit = "sv" },
    { "sv", "set string validation mode",
      OFFSET(string_validation), AV_OPT_TYPE_INT, {.i64=WRITER_STRING_VALIDATION_REPLACE}, 0, WRITER_STRING_VALIDATION_NB-1, .unit = "sv" },
    { "ignore",  NULL, 0, AV_OPT_TYPE_CONST, {.i64 = WRITER_STRING_VALIDATION_IGNORE},  .unit = "sv" },
    { "replace", NULL, 0, AV_OPT_TYPE_CONST, {.i64 = WRITER_STRING_VALIDATION_REPLACE}, .unit = "sv" },
    { "fail",    NULL, 0, AV_OPT_TYPE_CONST, {.i64 = WRITER_STRING_VALIDATION_FAIL},    .unit = "sv" },
    { "string_validation_replacement", "set string validation replacement string", OFFSET(string_validation_replacement), AV_OPT_TYPE_STRING, {.str=""}},
    { "svr", "set string validation replacement string", OFFSET(string_validation_replacement), AV_OPT_TYPE_STRING, {.str=""}},
    { NULL }
};

static void *writer_child_next(void *obj, void *prev)
{
    WriterContext *ctx = obj;
    if (!prev && ctx->writer && ctx->writer->priv_class && ctx->priv)
        return ctx->priv;
    return NULL;
}

static const AVClass writer_class = {
    .class_name = "Writer",
    .item_name  = writer_get_name,
    .option     = writer_options,
    .version    = LIBAVUTIL_VERSION_INT,
    .child_next = writer_child_next,
};

static void writer_close(WriterContext **wctx)
{
    int i;

    if (!*wctx)
        return;

    if ((*wctx)->writer->uninit)
        (*wctx)->writer->uninit(*wctx);
    for (i = 0; i < SECTION_MAX_NB_LEVELS; i++)
        av_bprint_finalize(&(*wctx)->section_pbuf[i], NULL);
    if ((*wctx)->writer->priv_class)
        av_opt_free((*wctx)->priv);
    av_freep(&((*wctx)->priv));
    av_freep(wctx);
}

static void bprint_bytes(AVBPrint *bp, const uint8_t *ubuf, size_t ubuf_size)
{
    int i;
    av_bprintf(bp, "0X");
    for (i = 0; i < ubuf_size; i++)
        av_bprintf(bp, "%02X", ubuf[i]);
}


static int writer_open(WriterContext **wctx, const Writer *writer, const char *args,
                       const struct section *sections, int nb_sections)
{
    int i, ret = 0;

    if (!(*wctx = av_mallocz(sizeof(WriterContext)))) {
        ret = AVERROR(ENOMEM);
        goto fail;
    }

    if (!((*wctx)->priv = av_mallocz(writer->priv_size))) {
        ret = AVERROR(ENOMEM);
        goto fail;
    }

    (*wctx)->class = &writer_class;
    (*wctx)->writer = writer;
    (*wctx)->level = -1;
    (*wctx)->sections = sections;
    (*wctx)->nb_sections = nb_sections;

    av_opt_set_defaults(*wctx);

    if (writer->priv_class) {
        void *priv_ctx = (*wctx)->priv;
        *((const AVClass **)priv_ctx) = writer->priv_class;
        av_opt_set_defaults(priv_ctx);
    }

    /* convert options to dictionary */
    if (args) {
        AVDictionary *opts = NULL;
        AVDictionaryEntry *opt = NULL;

        if ((ret = av_dict_parse_string(&opts, args, "=", ":", 0)) < 0) {
            av_log(*wctx, AV_LOG_ERROR, "Failed to parse option string '%s' provided to writer context\n", args);
            av_dict_free(&opts);
            goto fail;
        }

        while ((opt = av_dict_get(opts, "", opt, AV_DICT_IGNORE_SUFFIX))) {
            if ((ret = av_opt_set(*wctx, opt->key, opt->value, AV_OPT_SEARCH_CHILDREN)) < 0) {
                av_log(*wctx, AV_LOG_ERROR, "Failed to set option '%s' with value '%s' provided to writer context\n",
                       opt->key, opt->value);
                av_dict_free(&opts);
                goto fail;
            }
        }

        av_dict_free(&opts);
    }

    /* validate replace string */
    {
        const uint8_t *p = (*wctx)->string_validation_replacement;
        const uint8_t *endp = p + strlen(p);
        while (*p) {
            const uint8_t *p0 = p;
            int32_t code;
            ret = av_utf8_decode(&code, &p, endp, (*wctx)->string_validation_utf8_flags);
            if (ret < 0) {
                AVBPrint bp;
                av_bprint_init(&bp, 0, AV_BPRINT_SIZE_AUTOMATIC);
                bprint_bytes(&bp, p0, p-p0),
                    av_log(wctx, AV_LOG_ERROR,
                           "Invalid UTF8 sequence %s found in string validation replace '%s'\n",
                           bp.str, (*wctx)->string_validation_replacement);
                return ret;
            }
        }
    }

    for (i = 0; i < SECTION_MAX_NB_LEVELS; i++)
        av_bprint_init(&(*wctx)->section_pbuf[i], 1, AV_BPRINT_SIZE_UNLIMITED);

    if ((*wctx)->writer->init)
        ret = (*wctx)->writer->init(*wctx);
    if (ret < 0)
        goto fail;

    return 0;

fail:
    writer_close(wctx);
    return ret;
}

static inline void writer_print_section_header(WriterContext *wctx,
                                               int section_id)
{
    int parent_section_id;
    wctx->level++;
    av_assert0(wctx->level < SECTION_MAX_NB_LEVELS);
    parent_section_id = wctx->level ?
        (wctx->section[wctx->level-1])->id : SECTION_ID_NONE;

    wctx->nb_item[wctx->level] = 0;
    wctx->section[wctx->level] = &wctx->sections[section_id];

    if (section_id == SECTION_ID_PACKETS_AND_FRAMES) {
        wctx->nb_section_packet = wctx->nb_section_frame =
        wctx->nb_section_packet_frame = 0;
    } else if (parent_section_id == SECTION_ID_PACKETS_AND_FRAMES) {
        wctx->nb_section_packet_frame = section_id == SECTION_ID_PACKET ?
            wctx->nb_section_packet : wctx->nb_section_frame;
    }

    if (wctx->writer->print_section_header)
        wctx->writer->print_section_header(wctx);
}

static inline void writer_print_section_footer(WriterContext *wctx)
{
    int section_id = wctx->section[wctx->level]->id;
    int parent_section_id = wctx->level ?
        wctx->section[wctx->level-1]->id : SECTION_ID_NONE;

    if (parent_section_id != SECTION_ID_NONE)
        wctx->nb_item[wctx->level-1]++;
    if (parent_section_id == SECTION_ID_PACKETS_AND_FRAMES) {
        if (section_id == SECTION_ID_PACKET) wctx->nb_section_packet++;
        else                                     wctx->nb_section_frame++;
    }
    if (wctx->writer->print_section_footer)
        wctx->writer->print_section_footer(wctx);
    wctx->level--;
}

static inline void writer_print_integer(WriterContext *wctx,
                                        const char *key, long long int val)
{
    const struct section *section = wctx->section[wctx->level];

    if (section->show_all_entries || av_dict_get(section->entries_to_show, key, NULL, 0)) {
        wctx->writer->print_integer(wctx, key, val);
        wctx->nb_item[wctx->level]++;
    }
}

static inline int validate_string(WriterContext *wctx, char **dstp, const char *src)
{
    const uint8_t *p, *endp;
    AVBPrint dstbuf;
    int invalid_chars_nb = 0, ret = 0;

    av_bprint_init(&dstbuf, 0, AV_BPRINT_SIZE_UNLIMITED);

    endp = src + strlen(src);
    for (p = (uint8_t *)src; *p;) {
        uint32_t code;
        int invalid = 0;
        const uint8_t *p0 = p;

        if (av_utf8_decode(&code, &p, endp, wctx->string_validation_utf8_flags) < 0) {
            AVBPrint bp;
            av_bprint_init(&bp, 0, AV_BPRINT_SIZE_AUTOMATIC);
            bprint_bytes(&bp, p0, p-p0);
            av_log(wctx, AV_LOG_DEBUG,
                   "Invalid UTF-8 sequence %s found in string '%s'\n", bp.str, src);
            invalid = 1;
        }

        if (invalid) {
            invalid_chars_nb++;

            switch (wctx->string_validation) {
            case WRITER_STRING_VALIDATION_FAIL:
                av_log(wctx, AV_LOG_ERROR,
                       "Invalid UTF-8 sequence found in string '%s'\n", src);
                ret = AVERROR_INVALIDDATA;
                goto end;
                break;

            case WRITER_STRING_VALIDATION_REPLACE:
                av_bprintf(&dstbuf, "%s", wctx->string_validation_replacement);
                break;
            }
        }

        if (!invalid || wctx->string_validation == WRITER_STRING_VALIDATION_IGNORE)
            av_bprint_append_data(&dstbuf, p0, p-p0);
    }

    if (invalid_chars_nb && wctx->string_validation == WRITER_STRING_VALIDATION_REPLACE) {
        av_log(wctx, AV_LOG_WARNING,
               "%d invalid UTF-8 sequence(s) found in string '%s', replaced with '%s'\n",
               invalid_chars_nb, src, wctx->string_validation_replacement);
    }

end:
    av_bprint_finalize(&dstbuf, dstp);
    return ret;
}

#define PRINT_STRING_OPT      1
#define PRINT_STRING_VALIDATE 2

static inline int writer_print_string(WriterContext *wctx,
                                      const char *key, const char *val, int flags)
{
    const struct section *section = wctx->section[wctx->level];
    int ret = 0;

    if ((flags & PRINT_STRING_OPT)
        && !(wctx->writer->flags & WRITER_FLAG_DISPLAY_OPTIONAL_FIELDS))
        return 0;

    if (section->show_all_entries || av_dict_get(section->entries_to_show, key, NULL, 0)) {
        if (flags & PRINT_STRING_VALIDATE) {
            char *key1 = NULL, *val1 = NULL;
            ret = validate_string(wctx, &key1, key);
            if (ret < 0) goto end;
            ret = validate_string(wctx, &val1, val);
            if (ret < 0) goto end;
            wctx->writer->print_string(wctx, key1, val1);
        end:
            if (ret < 0) {
                av_log(wctx, AV_LOG_ERROR,
                       "Invalid key=value string combination %s=%s in section %s\n",
                       key, val, section->unique_name);
            }
            av_free(key1);
            av_free(val1);
        } else {
            wctx->writer->print_string(wctx, key, val);
        }

        wctx->nb_item[wctx->level]++;
    }

    return ret;
}

static inline void writer_print_rational(WriterContext *wctx,
                                         const char *key, AVRational q, char sep)
{
    AVBPrint buf;
    av_bprint_init(&buf, 0, AV_BPRINT_SIZE_AUTOMATIC);
    av_bprintf(&buf, "%d%c%d", q.num, sep, q.den);
    writer_print_string(wctx, key, buf.str, 0);
}

static void writer_print_time(WriterContext *wctx, const char *key,
                              int64_t ts, const AVRational *time_base, int is_duration)
{
    char buf[128];

    if ((!is_duration && ts == AV_NOPTS_VALUE) || (is_duration && ts == 0)) {
        writer_print_string(wctx, key, "N/A", PRINT_STRING_OPT);
    } else {
        double d = ts * av_q2d(*time_base);
        struct unit_value uv;
        uv.val.d = d;
        uv.unit = unit_second_str;
        value_string(buf, sizeof(buf), uv);
        writer_print_string(wctx, key, buf, 0);
    }
}

static void writer_print_ts(WriterContext *wctx, const char *key, int64_t ts, int is_duration)
{
    if ((!is_duration && ts == AV_NOPTS_VALUE) || (is_duration && ts == 0)) {
        writer_print_string(wctx, key, "N/A", PRINT_STRING_OPT);
    } else {
        writer_print_integer(wctx, key, ts);
    }
}

static void writer_print_data(WriterContext *wctx, const char *name,
                              uint8_t *data, int size)
{
    AVBPrint bp;
    int offset = 0, l, i;

    av_bprint_init(&bp, 0, AV_BPRINT_SIZE_UNLIMITED);
    av_bprintf(&bp, "\n");
    while (size) {
        av_bprintf(&bp, "%08x: ", offset);
        l = FFMIN(size, 16);
        for (i = 0; i < l; i++) {
            av_bprintf(&bp, "%02x", data[i]);
            if (i & 1)
                av_bprintf(&bp, " ");
        }
        av_bprint_chars(&bp, ' ', 41 - 2 * i - i / 2);
        for (i = 0; i < l; i++)
            av_bprint_chars(&bp, data[i] - 32U < 95 ? data[i] : '.', 1);
        av_bprintf(&bp, "\n");
        offset += l;
        data   += l;
        size   -= l;
    }
    writer_print_string(wctx, name, bp.str, 0);
    av_bprint_finalize(&bp, NULL);
}

#define MAX_REGISTERED_WRITERS_NB 64

static const Writer *registered_writers[MAX_REGISTERED_WRITERS_NB + 1];

static int writer_register(const Writer *writer)
{
    static int next_registered_writer_idx = 0;

    if (next_registered_writer_idx == MAX_REGISTERED_WRITERS_NB)
        return AVERROR(ENOMEM);

    registered_writers[next_registered_writer_idx++] = writer;
    return 0;
}

static const Writer *writer_get_by_name(const char *name)
{
    int i;

    for (i = 0; registered_writers[i]; i++)
        if (!strcmp(registered_writers[i]->name, name))
            return registered_writers[i];

    return NULL;
}


/* WRITERS */

#define DEFINE_WRITER_CLASS(name)                   \
static const char *name##_get_name(void *ctx)       \
{                                                   \
    return #name ;                                  \
}                                                   \
static const AVClass name##_class = {               \
    .class_name = #name,                            \
    .item_name  = name##_get_name,                  \
    .option     = name##_options                    \
}

/* Default output */

typedef struct DefaultContext {
    const AVClass *class;
    int nokey;
    int noprint_wrappers;
    int nested_section[SECTION_MAX_NB_LEVELS];
} DefaultContext;

#undef OFFSET
#define OFFSET(x) offsetof(DefaultContext, x)

static const AVOption default_options[] = {
    { "noprint_wrappers", "do not print headers and footers", OFFSET(noprint_wrappers), AV_OPT_TYPE_INT, {.i64=0}, 0, 1 },
    { "nw",               "do not print headers and footers", OFFSET(noprint_wrappers), AV_OPT_TYPE_INT, {.i64=0}, 0, 1 },
    { "nokey",          "force no key printing",     OFFSET(nokey),          AV_OPT_TYPE_INT, {.i64=0}, 0, 1 },
    { "nk",             "force no key printing",     OFFSET(nokey),          AV_OPT_TYPE_INT, {.i64=0}, 0, 1 },
    {NULL},
};

DEFINE_WRITER_CLASS(default);

/* lame uppercasing routine, assumes the string is lower case ASCII */
static inline char *upcase_string(char *dst, size_t dst_size, const char *src)
{
    int i;
    for (i = 0; src[i] && i < dst_size-1; i++)
        dst[i] = av_toupper(src[i]);
    dst[i] = 0;
    return dst;
}

static void default_print_section_header(WriterContext *wctx)
{
    DefaultContext *def = wctx->priv;
    char buf[32];
    const struct section *section = wctx->section[wctx->level];
    const struct section *parent_section = wctx->level ?
        wctx->section[wctx->level-1] : NULL;

    av_bprint_clear(&wctx->section_pbuf[wctx->level]);
    if (parent_section &&
        !(parent_section->flags & (SECTION_FLAG_IS_WRAPPER|SECTION_FLAG_IS_ARRAY))) {
        def->nested_section[wctx->level] = 1;
        av_bprintf(&wctx->section_pbuf[wctx->level], "%s%s:",
                   wctx->section_pbuf[wctx->level-1].str,
                   upcase_string(buf, sizeof(buf),
                                 av_x_if_null(section->element_name, section->name)));
    }

    if (def->noprint_wrappers || def->nested_section[wctx->level])
        return;

    if (!(section->flags & (SECTION_FLAG_IS_WRAPPER|SECTION_FLAG_IS_ARRAY)))
        printf("[%s]\n", upcase_string(buf, sizeof(buf), section->name));
}

static void default_print_section_footer(WriterContext *wctx)
{
    DefaultContext *def = wctx->priv;
    const struct section *section = wctx->section[wctx->level];
    char buf[32];

    if (def->noprint_wrappers || def->nested_section[wctx->level])
        return;

    if (!(section->flags & (SECTION_FLAG_IS_WRAPPER|SECTION_FLAG_IS_ARRAY)))
        printf("[/%s]\n", upcase_string(buf, sizeof(buf), section->name));
}

static void default_print_str(WriterContext *wctx, const char *key, const char *value)
{
    DefaultContext *def = wctx->priv;

    if (!def->nokey)
        printf("%s%s=", wctx->section_pbuf[wctx->level].str, key);
    printf("%s\n", value);
}

static void default_print_int(WriterContext *wctx, const char *key, long long int value)
{
    DefaultContext *def = wctx->priv;

    if (!def->nokey)
        printf("%s%s=", wctx->section_pbuf[wctx->level].str, key);
    printf("%lld\n", value);
}

static const Writer default_writer = {
    .name                  = "default",
    .priv_size             = sizeof(DefaultContext),
    .print_section_header  = default_print_section_header,
    .print_section_footer  = default_print_section_footer,
    .print_integer         = default_print_int,
    .print_string          = default_print_str,
    .flags = WRITER_FLAG_DISPLAY_OPTIONAL_FIELDS,
    .priv_class            = &default_class,
};

/* Compact output */

/**
 * Apply C-language-like string escaping.
 */
static const char *c_escape_str(AVBPrint *dst, const char *src, const char sep, void *log_ctx)
{
    const char *p;

    for (p = src; *p; p++) {
        switch (*p) {
        case '\b': av_bprintf(dst, "%s", "\\b");  break;
        case '\f': av_bprintf(dst, "%s", "\\f");  break;
        case '\n': av_bprintf(dst, "%s", "\\n");  break;
        case '\r': av_bprintf(dst, "%s", "\\r");  break;
        case '\\': av_bprintf(dst, "%s", "\\\\"); break;
        default:
            if (*p == sep)
                av_bprint_chars(dst, '\\', 1);
            av_bprint_chars(dst, *p, 1);
        }
    }
    return dst->str;
}

/**
 * Quote fields containing special characters, check RFC4180.
 */
static const char *csv_escape_str(AVBPrint *dst, const char *src, const char sep, void *log_ctx)
{
    char meta_chars[] = { sep, '"', '\n', '\r', '\0' };
    int needs_quoting = !!src[strcspn(src, meta_chars)];

    if (needs_quoting)
        av_bprint_chars(dst, '"', 1);

    for (; *src; src++) {
        if (*src == '"')
            av_bprint_chars(dst, '"', 1);
        av_bprint_chars(dst, *src, 1);
    }
    if (needs_quoting)
        av_bprint_chars(dst, '"', 1);
    return dst->str;
}

static const char *none_escape_str(AVBPrint *dst, const char *src, const char sep, void *log_ctx)
{
    return src;
}

typedef struct CompactContext {
    const AVClass *class;
    char *item_sep_str;
    char item_sep;
    int nokey;
    int print_section;
    char *escape_mode_str;
    const char * (*escape_str)(AVBPrint *dst, const char *src, const char sep, void *log_ctx);
    int nested_section[SECTION_MAX_NB_LEVELS];
    int has_nested_elems[SECTION_MAX_NB_LEVELS];
    int terminate_line[SECTION_MAX_NB_LEVELS];
} CompactContext;

#undef OFFSET
#define OFFSET(x) offsetof(CompactContext, x)

static const AVOption compact_options[]= {
    {"item_sep", "set item separator",    OFFSET(item_sep_str),    AV_OPT_TYPE_STRING, {.str="|"},  CHAR_MIN, CHAR_MAX },
    {"s",        "set item separator",    OFFSET(item_sep_str),    AV_OPT_TYPE_STRING, {.str="|"},  CHAR_MIN, CHAR_MAX },
    {"nokey",    "force no key printing", OFFSET(nokey),           AV_OPT_TYPE_INT,    {.i64=0},    0,        1        },
    {"nk",       "force no key printing", OFFSET(nokey),           AV_OPT_TYPE_INT,    {.i64=0},    0,        1        },
    {"escape",   "set escape mode",       OFFSET(escape_mode_str), AV_OPT_TYPE_STRING, {.str="c"},  CHAR_MIN, CHAR_MAX },
    {"e",        "set escape mode",       OFFSET(escape_mode_str), AV_OPT_TYPE_STRING, {.str="c"},  CHAR_MIN, CHAR_MAX },
    {"print_section", "print section name", OFFSET(print_section), AV_OPT_TYPE_INT,    {.i64=1},    0,        1        },
    {"p",             "print section name", OFFSET(print_section), AV_OPT_TYPE_INT,    {.i64=1},    0,        1        },
    {NULL},
};

DEFINE_WRITER_CLASS(compact);

static av_cold int compact_init(WriterContext *wctx)
{
    CompactContext *compact = wctx->priv;

    if (strlen(compact->item_sep_str) != 1) {
        av_log(wctx, AV_LOG_ERROR, "Item separator '%s' specified, but must contain a single character\n",
               compact->item_sep_str);
        return AVERROR(EINVAL);
    }
    compact->item_sep = compact->item_sep_str[0];

    if      (!strcmp(compact->escape_mode_str, "none")) compact->escape_str = none_escape_str;
    else if (!strcmp(compact->escape_mode_str, "c"   )) compact->escape_str = c_escape_str;
    else if (!strcmp(compact->escape_mode_str, "csv" )) compact->escape_str = csv_escape_str;
    else {
        av_log(wctx, AV_LOG_ERROR, "Unknown escape mode '%s'\n", compact->escape_mode_str);
        return AVERROR(EINVAL);
    }

    return 0;
}

static void compact_print_section_header(WriterContext *wctx)
{
    CompactContext *compact = wctx->priv;
    const struct section *section = wctx->section[wctx->level];
    const struct section *parent_section = wctx->level ?
        wctx->section[wctx->level-1] : NULL;
    compact->terminate_line[wctx->level] = 1;
    compact->has_nested_elems[wctx->level] = 0;

    av_bprint_clear(&wctx->section_pbuf[wctx->level]);
    if (!(section->flags & SECTION_FLAG_IS_ARRAY) && parent_section &&
        !(parent_section->flags & (SECTION_FLAG_IS_WRAPPER|SECTION_FLAG_IS_ARRAY))) {
        compact->nested_section[wctx->level] = 1;
        compact->has_nested_elems[wctx->level-1] = 1;
        av_bprintf(&wctx->section_pbuf[wctx->level], "%s%s:",
                   wctx->section_pbuf[wctx->level-1].str,
                   (char *)av_x_if_null(section->element_name, section->name));
        wctx->nb_item[wctx->level] = wctx->nb_item[wctx->level-1];
    } else {
        if (parent_section && compact->has_nested_elems[wctx->level-1] &&
            (section->flags & SECTION_FLAG_IS_ARRAY)) {
            compact->terminate_line[wctx->level-1] = 0;
            printf("\n");
        }
        if (compact->print_section &&
            !(section->flags & (SECTION_FLAG_IS_WRAPPER|SECTION_FLAG_IS_ARRAY)))
            printf("%s%c", section->name, compact->item_sep);
    }
}

static void compact_print_section_footer(WriterContext *wctx)
{
    CompactContext *compact = wctx->priv;

    if (!compact->nested_section[wctx->level] &&
        compact->terminate_line[wctx->level] &&
        !(wctx->section[wctx->level]->flags & (SECTION_FLAG_IS_WRAPPER|SECTION_FLAG_IS_ARRAY)))
        printf("\n");
}

static void compact_print_str(WriterContext *wctx, const char *key, const char *value)
{
    CompactContext *compact = wctx->priv;
    AVBPrint buf;

    if (wctx->nb_item[wctx->level]) printf("%c", compact->item_sep);
    if (!compact->nokey)
        printf("%s%s=", wctx->section_pbuf[wctx->level].str, key);
    av_bprint_init(&buf, 1, AV_BPRINT_SIZE_UNLIMITED);
    printf("%s", compact->escape_str(&buf, value, compact->item_sep, wctx));
    av_bprint_finalize(&buf, NULL);
}

static void compact_print_int(WriterContext *wctx, const char *key, long long int value)
{
    CompactContext *compact = wctx->priv;

    if (wctx->nb_item[wctx->level]) printf("%c", compact->item_sep);
    if (!compact->nokey)
        printf("%s%s=", wctx->section_pbuf[wctx->level].str, key);
    printf("%lld", value);
}

static const Writer compact_writer = {
    .name                 = "compact",
    .priv_size            = sizeof(CompactContext),
    .init                 = compact_init,
    .print_section_header = compact_print_section_header,
    .print_section_footer = compact_print_section_footer,
    .print_integer        = compact_print_int,
    .print_string         = compact_print_str,
    .flags = WRITER_FLAG_DISPLAY_OPTIONAL_FIELDS,
    .priv_class           = &compact_class,
};

/* CSV output */

#undef OFFSET
#define OFFSET(x) offsetof(CompactContext, x)

static const AVOption csv_options[] = {
    {"item_sep", "set item separator",    OFFSET(item_sep_str),    AV_OPT_TYPE_STRING, {.str=","},  CHAR_MIN, CHAR_MAX },
    {"s",        "set item separator",    OFFSET(item_sep_str),    AV_OPT_TYPE_STRING, {.str=","},  CHAR_MIN, CHAR_MAX },
    {"nokey",    "force no key printing", OFFSET(nokey),           AV_OPT_TYPE_INT,    {.i64=1},    0,        1        },