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

[James Almer <jamrial@gmail.com>]

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@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.

> 
>>   };
>>   
>>   static inline int get_object_type(GetBitContext *gb)
>> diff --git a/libavcodec/mpeg4audio.h b/libavcodec/mpeg4audio.h
>> index a6f71cff58..56615ef321 100644
>> --- a/libavcodec/mpeg4audio.h
>> +++ b/libavcodec/mpeg4audio.h
>> @@ -42,7 +42,7 @@ typedef struct MPEG4AudioConfig {
>>   } MPEG4AudioConfig;
>>   
>>   extern const int     ff_mpeg4audio_sample_rates[16];
>> -extern const uint8_t ff_mpeg4audio_channels[14];
>> +extern const uint8_t ff_mpeg4audio_channels[15];
>>   
>>   /**
>>    * Parse MPEG-4 systems extradata from a potentially unaligned GetBitContext to retrieve audio configuration.
> 
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