On 2021-07-13 13:14, Anton Khirnov wrote:
Quoting Gyan Doshi (2021-07-02 12:03:05)
Allows forcing decoders of different media type.
Needed to decode media data muxed as data streams.
---
doc/ffmpeg.texi | 5 +++++
fftools/ffmpeg_opt.c | 7 ++++++-
2 files changed, 11 insertions(+), 1 deletion(-)
diff --git a/doc/ffmpeg.texi b/doc/ffmpeg.texi
index 7827291755..c1065086e5 100644
--- a/doc/ffmpeg.texi
+++ b/doc/ffmpeg.texi
@@ -449,6 +449,11 @@ output file already exists.
Set number of times input stream shall be looped. Loop 0 means no loop,
loop -1 means infinite loop.
+@item -recast_media (@emph{global})
+Enable to allow forcing a decoder of a different media type than
+the one detected or designated by the demuxer. Useful for decoding
+media data muxed as data streams.
+
@item -c[:@var{stream_specifier}] @var{codec} (@emph{input/output,per-stream})
@itemx -codec[:@var{stream_specifier}] @var{codec}
(@emph{input/output,per-stream})
Select an encoder (when used before an output file) or a decoder (when used
diff --git a/fftools/ffmpeg_opt.c b/fftools/ffmpeg_opt.c
index a63bed54cf..76a220c21c 100644
--- a/fftools/ffmpeg_opt.c
+++ b/fftools/ffmpeg_opt.c
@@ -186,6 +186,7 @@ static int input_sync;
static int input_stream_potentially_available = 0;
static int ignore_unknown_streams = 0;
static int copy_unknown_streams = 0;
+static int recast_media = 0;
static int find_stream_info = 1;
static void uninit_options(OptionsContext *o)
@@ -759,7 +760,7 @@ static const AVCodec *find_codec_or_die(const char *name,
enum AVMediaType type,
av_log(NULL, AV_LOG_FATAL, "Unknown %s '%s'\n", codec_string, name);
exit_program(1);
}
- if (codec->type != type) {
+ if (codec->type != type && !recast_media) {
av_log(NULL, AV_LOG_FATAL, "Invalid %s type '%s'\n", codec_string,
name);
exit_program(1);
}
@@ -774,6 +775,8 @@ static const AVCodec *choose_decoder(OptionsContext *o,
AVFormatContext *s, AVSt
if (codec_name) {
const AVCodec *codec = find_codec_or_die(codec_name,
st->codecpar->codec_type, 0);
st->codecpar->codec_id = codec->id;
+ if (recast_media && st->codecpar->codec_type != codec->type)
+ st->codecpar->codec_type = codec->type;
The caller is not allowed to modify this struct for demuxing. This might
confuse demuxers that expect the values they put there to remain
choose_decoder() is called from within add_input_streams().
Near the end of this parent function, we have
ret = avcodec_parameters_from_context(par, ist->dec_ctx);
where par is
AVCodecParameters *par = st->codecpar;
avcodec_parameters_from_context(), starts with
{
codec_parameters_reset(par); --> sets codec_type to
AVMEDIA_TYPE_UNKNOWN
par->codec_type = codec->codec_type;
...
}
So it's already being done. I did an immediate recast to avoid some
temporary variables as the media type is used in a few switch blocks
after the decoder is set.
But that way also works for me, if you insist.
Regards,
Gyan
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