[FFmpeg-devel] [PATCH 1/2] avformat/mov: ensure the IAMF track is the first

[James Almer]

On 8/1/2024 9:35 AM, James Almer wrote:
> On 8/1/2024 5:59 AM, Anton Khirnov wrote:
>> Quoting James Almer (2024-08-01 04:14:09)
>>> Fixes crashes when muxing video tracks alongside IAMF ones.
>>>
>>> Signed-off-by: James Almer <jamrial at gmail.com>
>>> ---
>>>   libavformat/movenc.c | 11 ++++++++++-
>>>   1 file changed, 10 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/libavformat/movenc.c b/libavformat/movenc.c
>>> index ae49582a1a..87ec368d52 100644
>>> --- a/libavformat/movenc.c
>>> +++ b/libavformat/movenc.c
>>> @@ -7536,6 +7536,7 @@ static int mov_init_iamf_track(AVFormatContext *s)
>>>       if (!track->iamf)
>>>           return AVERROR(ENOMEM);
>>> +    track->first_iamf_idx = INT_MAX;
>>>       for (int i = 0; i < s->nb_stream_groups; i++) {
>>>           const AVStreamGroup *stg = s->stream_groups[i];
>>>           switch(stg->type) {
>>> @@ -7558,6 +7559,11 @@ static int mov_init_iamf_track(AVFormatContext 
>>> *s)
>>>               return ret;
>>>       }
>>> +    if (track->first_iamf_idx != 0) {
>>> +        av_log(s, AV_LOG_ERROR, "The IMAF track must be the first 
>>> track\n");
>>
>> Why? And is this documented anywhere?
> 
> Just comments in the code. The reason i wrote it this way is because i 
> parse the stream groups first, then the remaining streams, and generate 
> the tracks in that order, as it was the simplest, least invasive way 
> (The muxer handled streams and tracks as separate concepts with 
> potentially different count for each of them even before iamf).
> 
> I could look into changing it, but it may require some restructuring.

Ok, gave it a try and seemingly found out how to get this working 
without too many changes.
Will send an updated patch.