Native AAC encoder does not signal 7.1 correctly

[Anton1699]

This is the list of channel layouts the AAC encoder will encode without a PCE:

static const AVChannelLayout aac_normal_chan_layouts[7] = {
    AV_CHANNEL_LAYOUT_MONO,
    AV_CHANNEL_LAYOUT_STEREO,
    AV_CHANNEL_LAYOUT_SURROUND,
    AV_CHANNEL_LAYOUT_4POINT0,
    AV_CHANNEL_LAYOUT_5POINT0_BACK,
    AV_CHANNEL_LAYOUT_5POINT1_BACK,
    AV_CHANNEL_LAYOUT_7POINT1,
};

Looking at the 7.1 Channel Support table ​here, it seems that the seventh channel layout signals ​SDDS (Sony Dynamic Digital Sound) which FFmpeg calls 7.1(wide). FFmpeg's 7.1 is signaled using the twelfth entry which was added in an amendment to the AAC specification.

I understand that not every decoder will understand the amended channel layouts so maybe there should be a command line flag to manually enable them.

[pkv]

i agree. In my fork I've set indeed to AV_CH_LAYOUT_7POINT1_WIDE instead of AV_CHANNEL_LAYOUT_7POINT1

[Balling]

FFmpeg's 7.1 is signaled using the twelfth entry which was added in an amendment to the AAC specification.

Well, yes, that is for Blu-ray though. In 2bad226f89683d1a6795512855fff69b36e09c97 AV_CHANNEL_LAYOUT_7POINT1_WIDE_BACK added, disabled in favor of PCE configuration,

and AV_CHANNEL_LAYOUT_7POINT1 is finally moved to 12th place.

PCE can still be further enabled.