Re: [FFmpeg-devel] [PATCH] ffprobe: add -codec:<media_spec> option

[Maryla Ustarroz via ffmpeg-devel <ffmpeg-devel@ffmpeg.org>]

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From: Maryla Ustarroz <maryla@google.com>
To: FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org>
Subject: Re: [FFmpeg-devel] [PATCH] ffprobe: add -codec:<media_spec> option
Date: Thu, 19 Jun 2025 17:02:50 +0200
Message-ID: <CA+yX6GGk9n0d64qn9Trr98zpUvLFXd12JwdCMumw9sMiwFszEg@mail.gmail.com>

Friendly ping.
This feature came up during the review of "[PATCH 2/2] avcodec/libaom:
Add tests for HDR10+ metadata support"
https://ffmpeg.org/pipermail/ffmpeg-devel/2025-June/344683.html

On Tue, Jun 10, 2025 at 5:02 PM Maryla Ustarroz-Calonge via
ffmpeg-devel <ffmpeg-devel@ffmpeg.org> wrote:
>
>
>
>
> ---------- Forwarded message ----------
> From: Maryla Ustarroz-Calonge <maryla@google.com>
> To: ffmpeg-devel@ffmpeg.org
> Cc:
> Bcc:
> Date: Tue, 10 Jun 2025 17:02:05 +0200
> Subject: [PATCH] ffprobe: add -codec:<media_spec> option
> opt_codec() is mostly copied over from ffplay.c
>
> Signed-off-by: Maryla Ustarroz-Calonge <maryla@google.com>
> ---
>  Changelog         |   2 +-
>  fftools/ffprobe.c | 114 +++++++++++++++++++++++++++++++++++++++++-----
>  2 files changed, 103 insertions(+), 13 deletions(-)
>
> diff --git a/Changelog b/Changelog
> index 4217449438..ae73611222 100644
> --- a/Changelog
> +++ b/Changelog
> @@ -18,7 +18,7 @@ version <next>:
>  - APV encoding support through a libopenapv wrapper
>  - VVC decoder supports all content of SCC (Screen Content Coding):
>    IBC (Inter Block Copy), Palette Mode and ACT (Adaptive Color Transform
> -
> +- ffprobe -codec option
>
>  version 7.1:
>  - Raw Captions with Time (RCWT) closed caption demuxer
> diff --git a/fftools/ffprobe.c b/fftools/ffprobe.c
> index 1346ed33c5..0124ce114c 100644
> --- a/fftools/ffprobe.c
> +++ b/fftools/ffprobe.c
> @@ -36,6 +36,7 @@
>  #include "libavutil/ambient_viewing_environment.h"
>  #include "libavutil/avassert.h"
>  #include "libavutil/avstring.h"
> +#include "libavutil/avutil.h"
>  #include "libavutil/bprint.h"
>  #include "libavutil/channel_layout.h"
>  #include "libavutil/display.h"
> @@ -130,6 +131,11 @@ static int use_byte_value_binary_prefix = 0;
>  static int use_value_sexagesimal_format = 0;
>  static int show_private_data            = 1;
>
> +static const char *audio_codec_name = NULL;
> +static const char *data_codec_name = NULL;
> +static const char *subtitle_codec_name = NULL;
> +static const char *video_codec_name = NULL;
> +
>  #define SHOW_OPTIONAL_FIELDS_AUTO       -1
>  #define SHOW_OPTIONAL_FIELDS_NEVER       0
>  #define SHOW_OPTIONAL_FIELDS_ALWAYS      1
> @@ -2284,6 +2290,64 @@ static void show_error(AVTextFormatContext *tfc, int err)
>      avtext_print_section_footer(tfc);
>  }
>
> +static int get_decoder_by_name(const char *codec_name, const AVCodec **codec)
> +{
> +    if (codec_name == NULL)
> +        return 0;
> +
> +    *codec = avcodec_find_decoder_by_name(codec_name);
> +    if (*codec == NULL) {
> +        av_log(NULL, AV_LOG_ERROR,
> +                "No codec could be found with name '%s'\n", codec_name);
> +        return AVERROR(EINVAL);;
> +    }
> +    return 0;
> +}
> +
> +static int set_decoders(AVFormatContext *fmt_ctx)
> +{
> +    int ret;
> +    ret = get_decoder_by_name(audio_codec_name, &fmt_ctx->audio_codec);
> +    if (ret < 0) return ret;
> +    ret = get_decoder_by_name(data_codec_name, &fmt_ctx->data_codec);
> +    if (ret < 0) return ret;
> +    ret = get_decoder_by_name(subtitle_codec_name, &fmt_ctx->subtitle_codec);
> +    if (ret < 0) return ret;
> +    ret = get_decoder_by_name(video_codec_name, &fmt_ctx->video_codec);
> +    if (ret < 0) return ret;
> +    return 0;
> +}
> +
> +static const AVCodec *get_decoder_for_stream(AVFormatContext *fmt_ctx, AVStream *stream)
> +{
> +    const AVCodec *codec = NULL;
> +    switch (stream->codecpar->codec_type) {
> +        case AVMEDIA_TYPE_VIDEO:    codec = fmt_ctx->video_codec; break;
> +        case AVMEDIA_TYPE_AUDIO:    codec = fmt_ctx->audio_codec; break;
> +        case AVMEDIA_TYPE_SUBTITLE: codec = fmt_ctx->subtitle_codec; break;
> +        case AVMEDIA_TYPE_DATA:     codec = fmt_ctx->data_codec; break;
> +    }
> +
> +    if (codec != NULL)
> +        return codec;
> +
> +    if (stream->codecpar->codec_id == AV_CODEC_ID_PROBE) {
> +        av_log(NULL, AV_LOG_WARNING,
> +               "Failed to probe codec for input stream %d\n", stream->index);
> +        return NULL;
> +    }
> +
> +    codec = avcodec_find_decoder(stream->codecpar->codec_id);
> +    if (codec == NULL) {
> +        av_log(NULL, AV_LOG_WARNING,
> +               "Unsupported codec with id %d for input stream %d\n",
> +               stream->codecpar->codec_id, stream->index);
> +        return NULL;
> +    }
> +
> +    return codec;
> +}
> +
>  static int open_input_file(InputFile *ifile, const char *filename,
>                             const char *print_filename)
>  {
> @@ -2296,6 +2360,9 @@ static int open_input_file(InputFile *ifile, const char *filename,
>      if (!fmt_ctx)
>          return AVERROR(ENOMEM);
>
> +    err = set_decoders(fmt_ctx);
> +    if (err < 0)
> +        return err;
>      if (!av_dict_get(format_opts, "scan_all_pmts", NULL, AV_DICT_MATCH_CASE)) {
>          av_dict_set(&format_opts, "scan_all_pmts", "1", AV_DICT_DONT_OVERWRITE);
>          scan_all_pmts_set = 1;
> @@ -2350,20 +2417,10 @@ static int open_input_file(InputFile *ifile, const char *filename,
>
>          ist->st = stream;
>
> -        if (stream->codecpar->codec_id == AV_CODEC_ID_PROBE) {
> -            av_log(NULL, AV_LOG_WARNING,
> -                   "Failed to probe codec for input stream %d\n",
> -                    stream->index);
> +        codec = get_decoder_for_stream(fmt_ctx, stream);
> +        if (!codec)
>              continue;
> -        }
>
> -        codec = avcodec_find_decoder(stream->codecpar->codec_id);
> -        if (!codec) {
> -            av_log(NULL, AV_LOG_WARNING,
> -                    "Unsupported codec with id %d for input stream %d\n",
> -                    stream->codecpar->codec_id, stream->index);
> -            continue;
> -        }
>          {
>              AVDictionary *opts;
>
> @@ -2510,6 +2567,10 @@ end:
>      av_freep(&selected_streams);
>      av_freep(&streams_with_closed_captions);
>      av_freep(&streams_with_film_grain);
> +    av_freep(&audio_codec_name);
> +    av_freep(&data_codec_name);
> +    av_freep(&subtitle_codec_name);
> +    av_freep(&video_codec_name);
>
>      return ret;
>  }
> @@ -2964,6 +3025,34 @@ static int opt_sections(void *optctx, const char *opt, const char *arg)
>      return 0;
>  }
>
> +static int opt_codec(void *optctx, const char *opt, const char *arg)
> +{
> +   const char *spec = strchr(opt, ':');
> +   const char **name;
> +   if (!spec) {
> +       av_log(NULL, AV_LOG_ERROR,
> +              "No media specifier was specified for '%s' in option '%s'. Use -%s:<media_spec>\n",
> +               arg, opt, opt);
> +       return AVERROR(EINVAL);
> +   }
> +   spec++;
> +
> +   switch (spec[0]) {
> +   case 'a' : name = &audio_codec_name;    break;
> +   case 'd' : name = &data_codec_name;     break;
> +   case 's' : name = &subtitle_codec_name; break;
> +   case 'v' : name = &video_codec_name;    break;
> +   default:
> +       av_log(NULL, AV_LOG_ERROR,
> +              "Invalid media specifier '%s' in option '%s'. Must be one of: v, a, s, d\n", spec, opt);
> +       return AVERROR(EINVAL);
> +   }
> +
> +   av_freep(name);
> +   *name = av_strdup(arg);
> +   return *name ? 0 : AVERROR(ENOMEM);
> +}
> +
>  static int opt_show_versions(void *optctx, const char *opt, const char *arg)
>  {
>      mark_section_show_entries(SECTION_ID_PROGRAM_VERSION, 1, NULL);
> @@ -3039,6 +3128,7 @@ static const OptionDef real_options[] = {
>      { "print_filename",        OPT_TYPE_FUNC, OPT_FUNC_ARG, {.func_arg = opt_print_filename}, "override the printed input filename", "print_file"},
>      { "find_stream_info",      OPT_TYPE_BOOL, OPT_INPUT | OPT_EXPERT, { &find_stream_info },
>          "read and decode the streams to fill missing information with heuristics" },
> +    { "codec",                 OPT_TYPE_FUNC, OPT_FUNC_ARG, { .func_arg = opt_codec}, "force decoder", "decoder_name" },
>      { NULL, },
>  };
>
> --
> 2.50.0.rc1.591.g9c95f17f64-goog
>
>
>
>
> ---------- Forwarded message ----------
> From: Maryla Ustarroz-Calonge via ffmpeg-devel <ffmpeg-devel@ffmpeg.org>
> To: ffmpeg-devel@ffmpeg.org
> Cc: Maryla Ustarroz-Calonge <maryla@google.com>
> Bcc:
> Date: Tue, 10 Jun 2025 17:02:05 +0200
> Subject: [FFmpeg-devel] [PATCH] ffprobe: add -codec:<media_spec> option
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