[FFmpeg-devel] [PATCH v3] avformat/nutdec: Don't create inconsistent side data

[Michael Niedermayer]

On Thu, May 30, 2024 at 02:14:20AM +0200, Andreas Rheinhardt wrote:
> Forgotten in 65ddc74988245a01421a63c5cffa4d900c47117c.
> 
> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at outlook.com>
> ---
>  libavformat/nutdec.c | 14 ++++----------
>  1 file changed, 4 insertions(+), 10 deletions(-)
> 
> diff --git a/libavformat/nutdec.c b/libavformat/nutdec.c
> index 0bb7f154db..34b7e3cb9a 100644
> --- a/libavformat/nutdec.c
> +++ b/libavformat/nutdec.c
> @@ -881,8 +881,6 @@ static int read_sm_data(AVFormatContext *s, AVIOContext *bc, AVPacket *pkt, int
>      int count = ffio_read_varlen(bc);
>      int skip_start = 0;
>      int skip_end = 0;
> -    int channels = 0;
> -    int64_t channel_layout = 0;
>      int sample_rate = 0;
>      int width = 0;
>      int height = 0;
> @@ -930,7 +928,7 @@ static int read_sm_data(AVFormatContext *s, AVIOContext *bc, AVPacket *pkt, int
>                  AV_WB64(dst, v64);
>                  dst += 8;
>              } else if (!strcmp(name, "ChannelLayout") && value_len == 8) {
> -                channel_layout = avio_rl64(bc);
> +                // Ignored
>                  continue;
>              } else {
>                  av_log(s, AV_LOG_WARNING, "Unknown data %s / %s\n", name, type_str);
> @@ -952,7 +950,7 @@ static int read_sm_data(AVFormatContext *s, AVIOContext *bc, AVPacket *pkt, int
>              } else if (!strcmp(name, "SkipEnd")) {
>                  skip_end = value;
>              } else if (!strcmp(name, "Channels")) {
> -                channels = value;
> +                // Ignored
>              } else if (!strcmp(name, "SampleRate")) {
>                  sample_rate = value;
>              } else if (!strcmp(name, "Width")) {
> @@ -965,18 +963,14 @@ static int read_sm_data(AVFormatContext *s, AVIOContext *bc, AVPacket *pkt, int
>          }
>      }
>  
> -    if (channels || channel_layout || sample_rate || width || height) {
> -        uint8_t *dst = av_packet_new_side_data(pkt, AV_PKT_DATA_PARAM_CHANGE, 28);
> +    if (sample_rate || width || height) {
> +        uint8_t *dst = av_packet_new_side_data(pkt, AV_PKT_DATA_PARAM_CHANGE, 16);
>          if (!dst)
>              return AVERROR(ENOMEM);
>          bytestream_put_le32(&dst,
>                              AV_SIDE_DATA_PARAM_CHANGE_SAMPLE_RATE*(!!sample_rate) +
>                              AV_SIDE_DATA_PARAM_CHANGE_DIMENSIONS*(!!(width|height))
>                             );
> -        if (channels)
> -            bytestream_put_le32(&dst, channels);
> -        if (channel_layout)
> -            bytestream_put_le64(&dst, channel_layout);
>          if (sample_rate)
>              bytestream_put_le32(&dst, sample_rate);
>          if (width || height){

This would break mid stream changes to the channel layout & channels when it
is carried at format level only

The commit message also does not adequately explain why such mid stream changes
are ignored

thx

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Into a blind darkness they enter who follow after the Ignorance,
they as if into a greater darkness enter who devote themselves
to the Knowledge alone. -- Isha Upanishad
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