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

[Frank Plowman <post@frankplowman.com>]

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@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.

-- 
Frank
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