[FFmpeg-devel] [PATCH] lavc/vvc: Skip enhancement layer NAL units

[James Almer]

On 4/18/2024 5:19 PM, Frank Plowman wrote:
> On 18/04/2024 20:43, James Almer wrote:
>> On 4/18/2024 3:59 PM, Frank Plowman wrote:
>>> The native VVC decoder does not yet support quality/spatial/multiview
>>> scalability.  Bitstreams requiring this feature could cause crashes.
>>> Patch fixes this by skipping NAL units which are not in the base layer,
>>> warning the user while doing so.
>>>
>>> Signed-off-by: Frank Plowman <post at frankplowman.com>
>>> ---
>>>    libavcodec/vvc/dec.c | 5 +++++
>>>    1 file changed, 5 insertions(+)
>>>
>>> diff --git a/libavcodec/vvc/dec.c b/libavcodec/vvc/dec.c
>>> index a4fc40b40a..5249ddf989 100644
>>> --- a/libavcodec/vvc/dec.c
>>> +++ b/libavcodec/vvc/dec.c
>>> @@ -785,6 +785,11 @@ static int decode_nal_unit(VVCContext *s,
>>> VVCFrameContext *fc, const H2645NAL *n
>>>          s->temporal_id = nal->temporal_id;
>>>    +    if (nal->nuh_layer_id > 0) {
>>> +        avpriv_report_missing_feature(fc->log_ctx, "Multilayer");
>>
>> A more verbose message would be better.
>>
> 
> Thanks for your review James.
> 
> Would "Quality/spatial/multiview scalability" be better or do you have
> some other suggestion?  The message is put in a template by
> avpriv_report_missing_feature, e.g.
> 
> [vvc @ 0x618000003c80] Multilayer is not implemented. Update your FFmpeg
> version to the newest one from Git. If the problem still occurs, it
> means that your file has a feature which has not been implemented.
> 
> so the string passed to avpriv_report_missing_feature must be a noun.

Maybe "Decoding of multilayer bitstreams".