[FFmpeg-devel] [PATCH 2/3] lavfi: EBU R.128 channel weights

[Kieran Kunhya]

On Sat, Feb 2, 2013 at 12:02 PM, Clément Bœsch <ubitux at gmail.com> wrote:
> On Sat, Jan 19, 2013 at 08:24:53PM +0000, David A. Sedacca wrote:
>> Correct the recognition of channel layouts for good channel weight
>> in the loudness computation.
>> This suggested patch is 2 of 3 for Ticket #2144 "libavfilter ebur128
>> loudness inaccuracy, irregular time interval, LFE interference".
>>
>> Signed-off-by: David A. Sedacca" <sedacca at comcast.net>
>>
>> ---
>>
>> This updated patch submission updates the style of the 'if' block
>> per Clément's suggestion as clarified by Carl Eugen. It also
>> reverts to the original pre-patch behavior to not allocate integrator
>> cache memory for zero-weighted channels.
>>
>>  libavfilter/f_ebur128.c |   24 +++++++++++++++++++-----
>>  1 file changed, 19 insertions(+), 5 deletions(-)
>>
>> diff --git a/libavfilter/f_ebur128.c b/libavfilter/f_ebur128.c
>> index 85fddad..0265767 100644
>> --- a/libavfilter/f_ebur128.c
>> +++ b/libavfilter/f_ebur128.c
>> @@ -314,12 +314,15 @@ static int config_video_output(AVFilterLink *outlink)
>>  static int config_audio_output(AVFilterLink *outlink)
>>  {
>>      int i;
>> +    int idx_bitposn = 0;
>>      AVFilterContext *ctx = outlink->src;
>>      EBUR128Context *ebur128 = ctx->priv;
>>      const int nb_channels = av_get_channel_layout_nb_channels(outlink->channel_layout);
>>
>>  #define BACK_MASK (AV_CH_BACK_LEFT    |AV_CH_BACK_CENTER    |AV_CH_BACK_RIGHT| \
>> -                   AV_CH_TOP_BACK_LEFT|AV_CH_TOP_BACK_CENTER|AV_CH_TOP_BACK_RIGHT)
>> +                   AV_CH_TOP_BACK_LEFT|AV_CH_TOP_BACK_CENTER|AV_CH_TOP_BACK_RIGHT| \
>> +                   AV_CH_SIDE_LEFT                          |AV_CH_SIDE_RIGHT| \
>
>> +                   AV_CH_SURROUND_DIRECT_LEFT               |AV_CH_SURROUND_DIRECT_RIGHT)
>
> What is the meaning of this "direct" left/right? It sounds like a "front"
> speaker to me, but I may be wrong.

They are part of a 13.1 channel map and as far as I can tell they are
surround speakers. Anyway 13.1 is well-beyond the scope
of R.128. I think this patch should get committed if it fixes the test vectors.