[FFmpeg-devel] [PATCH 3/4 v2] avcodec/aacdec: add support for channel configuration 14

[Andreas Rheinhardt]

James Almer:
> On 10/28/2022 9:31 AM, Andreas Rheinhardt wrote:
>> James Almer:
>>> It corresponds to the 7.1(top) layout.
>>>
>>> Signed-off-by: James Almer <jamrial at gmail.com>
>>> ---
>>>   libavcodec/aacdec_template.c | 23 ++++++++++++++++++++++-
>>>   libavcodec/aacdectab.h       |  6 +++---
>>>   libavcodec/mpeg4audio.c      |  5 +++--
>>>   libavcodec/mpeg4audio.h      |  2 +-
>>>   4 files changed, 29 insertions(+), 7 deletions(-)
>>>
>>> diff --git a/libavcodec/aacdec_template.c b/libavcodec/aacdec_template.c
>>> index c10bc743b6..4b8e29ba71 100644
>>> --- a/libavcodec/aacdec_template.c
>>> +++ b/libavcodec/aacdec_template.c
>>> @@ -404,6 +404,21 @@ static uint64_t sniff_channel_order(uint8_t
>>> (*layout_map)[3], int tags)
>>>           i++;
>>>       }
>>>   +    // The previous checks would end up at 4 at this point for
>>> chan_config 14
>>> +    if (layout == AV_CH_LAYOUT_5POINT1 && tags == 5 && i == 4) {
>>> +        const uint8_t (*reference_layout_map)[3] =
>>> aac_channel_layout_map[13];
>>> +        for (int j = 0; j < tags; j++) {
>>> +            if (layout_map[j][0] != reference_layout_map[j][0] ||
>>> +                layout_map[j][2] != reference_layout_map[j][2])
>>> +                goto end_of_layout_definition;
>>> +        }
>>> +
>>> +        i += assign_pair(e2c_vec, layout_map, i,
>>> +                         AV_CH_TOP_FRONT_LEFT,
>>> +                         AV_CH_TOP_FRONT_RIGHT,
>>> +                         AAC_CHANNEL_FRONT,
>>> +                         &layout);
>>> +    }
>>>       // The previous checks would end up at 8 at this point for 22.2
>>>       if (layout == PREFIX_FOR_22POINT2 && tags == 16 && i == 8) {
>>>           const uint8_t (*reference_layout_map)[3] =
>>> aac_channel_layout_map[12];
>>> @@ -633,7 +648,7 @@ static int set_default_channel_config(AACContext
>>> *ac, AVCodecContext *avctx,
>>>                                         int channel_config)
>>>   {
>>>       if (channel_config < 1 || (channel_config > 7 && channel_config
>>> < 11) ||
>>> -        channel_config > 13) {
>>> +        channel_config > 14) {
>>>           av_log(avctx, AV_LOG_ERROR,
>>>                  "invalid default channel configuration (%d)\n",
>>>                  channel_config);
>>> @@ -717,6 +732,12 @@ static ChannelElement *get_che(AACContext *ac,
>>> int type, int elem_id)
>>>       /* For indexed channel configurations map the channels solely
>>> based
>>>        * on position. */
>>>       switch (ac->oc[1].m4ac.chan_config) {
>>> +    case 14:
>>> +        if (ac->tags_mapped > 2 && ((type == TYPE_CPE && elem_id <
>>> 3) ||
>>> +                                    (type == TYPE_LFE && elem_id <
>>> 1))) {
>>> +            ac->tags_mapped++;
>>> +            return ac->tag_che_map[type][elem_id] =
>>> ac->che[type][elem_id];
>>> +        }
>>>       case 13:
>>>           if (ac->tags_mapped > 3 && ((type == TYPE_CPE && elem_id <
>>> 8) ||
>>>                                       (type == TYPE_SCE && elem_id <
>>> 6) ||
>>> diff --git a/libavcodec/aacdectab.h b/libavcodec/aacdectab.h
>>> index b820f10556..e9bbd1fe13 100644
>>> --- a/libavcodec/aacdectab.h
>>> +++ b/libavcodec/aacdectab.h
>>> @@ -68,8 +68,8 @@ static const uint8_t
>>> aac_channel_layout_map[16][16][3] = {
>>>         { TYPE_SCE, 5, AAC_CHANNEL_FRONT }, // SCE6 = BtFC,
>>>         { TYPE_CPE, 7, AAC_CHANNEL_FRONT }, // CPE8 = BtFL and BtFR
>>>       },
>>> +    { { TYPE_SCE, 0, AAC_CHANNEL_FRONT }, { TYPE_CPE, 0,
>>> AAC_CHANNEL_FRONT }, { TYPE_CPE, 1, AAC_CHANNEL_SIDE }, { TYPE_LFE,
>>> 0, AAC_CHANNEL_LFE }, { TYPE_CPE, 2, AAC_CHANNEL_FRONT  }, },
>>>       { { 0, } },
>>> -    /* TODO: Add 7+1 TOP configuration */
>>>   };
>>>     #if FF_API_OLD_CHANNEL_LAYOUT
>>> @@ -84,8 +84,8 @@ static const uint64_t aac_channel_layout[] = {
>>>       AV_CH_LAYOUT_6POINT1,
>>>       AV_CH_LAYOUT_7POINT1,
>>>       AV_CH_LAYOUT_22POINT2,
>>> +    AV_CH_LAYOUT_7POINT1_TOP,
>>>       0,
>>> -    /* AV_CH_LAYOUT_7POINT1_TOP, */
>>>   };
>>>   #endif
>>>   @@ -100,8 +100,8 @@ static const AVChannelLayout aac_ch_layout[] = {
>>>       AV_CHANNEL_LAYOUT_6POINT1,
>>>       AV_CHANNEL_LAYOUT_7POINT1,
>>>       AV_CHANNEL_LAYOUT_22POINT2,
>>> +    AV_CHANNEL_LAYOUT_7POINT1_TOP,
>>>       { 0 },
>>> -    /* AV_CHANNEL_LAYOUT_7POINT1_TOP, */
>>>   };
>>>     #endif /* AVCODEC_AACDECTAB_H */
>>> diff --git a/libavcodec/mpeg4audio.c b/libavcodec/mpeg4audio.c
>>> index e38a8c0852..4a996411d1 100644
>>> --- a/libavcodec/mpeg4audio.c
>>> +++ b/libavcodec/mpeg4audio.c
>>> @@ -56,7 +56,7 @@ static int parse_config_ALS(GetBitContext *gb,
>>> MPEG4AudioConfig *c, void *logctx
>>>       return 0;
>>>   }
>>>   -const uint8_t ff_mpeg4audio_channels[14] = {
>>> +const uint8_t ff_mpeg4audio_channels[15] = {
>>>       0,
>>>       1, // mono (1/0)
>>>       2, // stereo (2/0)
>>> @@ -70,7 +70,8 @@ const uint8_t ff_mpeg4audio_channels[14] = {
>>>       0,
>>>       7, // 3/3.1
>>>       8, // 3/2/2.1
>>> -    24 // 3/3/3 - 5/2/3 - 3/0/0.2
>>> +    24, // 3/3/3 - 5/2/3 - 3/0/0.2
>>> +    8 // 3/2.1 - 2/0
>>
>> Is it guaranteed that 8 will always be the last element of this array?
>> If not, you should use "8,", so that the comma won't have to be added
>> when someone makes an addition in the future.
> 
> What does the pedantic gcc option say about this? I recall it complained
> about either having or missing the comma in the last element, so given
> that it makes no real difference I'd go with whatever keeps it quiet.
> 

You are confusing this with enum declarations: In C90, a trailing comma
was not allowed in their declaration; C99 lifted this restriction (we
have enums that make use of this). But trailing commas were always
allowed in initializers.

- Andreas

PS: Do you use -pedantic?