[FFmpeg-devel] [PATCH] avcodec/aac_parser: fix aac profile probing

[Baptiste Coudurier]

> On Jun 27, 2025, at 5:01 AM, Nicolas Gaullier <nicolas.gaullier at cji.paris> wrote:
> 
> On 6/26/25 19:30, Baptiste Coudurier wrote:
>> Hi Nicolas
>>> On Jun 26, 2025, at 4:06 AM, Nicolas Gaullier <nicolas.gaullier at cji.paris> wrote:
>>> 
>>> On 6/17/25 13:41, Nicolas Gaullier wrote:
>>>> Reverts 64bb91fd3b5a00a8849531c7e8dd207f2a626096 except the
>>>> key_frame setting for aac.
>>>> See also 696ea1c2236842572df88d573e24a39be3f19c98.
>>>> Don't force the profile as it may override the correct value
>>>> set by the decoder (HE/HEv2).
>>>> 
>>>> Fixes #11600
>>>> 
>>>> Signed-off-by: Nicolas Gaullier <nicolas.gaullier at cji.paris>
>>>> ---
>>>>  libavcodec/aac_ac3_parser.c | 8 +++-----
>>>>  1 file changed, 3 insertions(+), 5 deletions(-)
>>>> 
>>>> diff --git a/libavcodec/aac_ac3_parser.c b/libavcodec/aac_ac3_parser.c
>>>> index e10ce13a3b..1dcc2e735f 100644
>>>> --- a/libavcodec/aac_ac3_parser.c
>>>> +++ b/libavcodec/aac_ac3_parser.c
>>>> @@ -147,15 +147,13 @@ get_next:
>>>>          } else {
>>>>  #if CONFIG_AAC_PARSER
>>>>              AACADTSHeaderInfo hdr;
>>>> -            GetBitContext gb;
>>>>  -            init_get_bits8(&gb, buf, buf_size);
>>>>              if (buf_size < AV_AAC_ADTS_HEADER_SIZE ||
>>>> -                ff_adts_header_parse(&gb, &hdr) < 0)
>>>> +                ff_adts_header_parse_buf(buf, &hdr) < 0)
>>>>                  return i;
>>>>  -            avctx->profile = hdr.object_type - 1;
>>>> -            s1->key_frame = (avctx->profile == AV_PROFILE_AAC_USAC) ? get_bits1(&gb) : 1;
>>>> +            /* ADTS does not support USAC */
>>>> +            s1->key_frame = 1;
>>>>              bit_rate = hdr.bit_rate;
>>>>  #endif
>>>>          }
>>> Ping ?
>>> 
>>> https://patchwork.ffmpeg.org/project/ffmpeg/list/?series=14810
>>> 
>> How hard is it to detect HEAACv2 in the parser ? Maybe only set it if profile is unknown?
>> It’s usually nice when parser can set profile.
>> 
>> —
>> Baptiste
> 
> Yes, you're right, I had the same feeling when reverting this...
> 
> It does not seem so straightforward, because aac seems very modular while not using signaling, but it must be doable someway.
> 
> I will dig into this and see if I can come up with something satisfactory...
> 
> I think it would be an additional patch, and this one should remain the basic revert which, mostly, simply removes dead code.
> 
> Maybe it would be desirable to follow this patch immediately with a new patch that could restore the "profile setting" thing correctly, but that would add some undetermined delay, so I would say it is best to apply this patch on its own.

Yeah, does adding “if avctx->profile == UNKNOWN” fix the ticket?

— 
Baptiste Coudurier