[FFmpeg-devel] [PATCH v2 1/8] aacpsy: use a different metric for the spread of a band

[Claudio Freire]

On Thu, Jul 2, 2015 at 3:13 PM, Rostislav Pehlivanov
<atomnuker at gmail.com> wrote:
> This commit modifies 02dbed6 to use band->active_lines to better gauge how much information is contained within a single band and thus allow the perceptual noise subsitution to more accurately determine which bands to code as noise. The spread[w+g] used before this patch behaved more like a low-pass filter for PNS band_types, which could mistakingly mark some low frequency bands as noise.
>
> Reviewed-by: Claudio Freire <klaussfreire at gmail.com>
> ---
>  libavcodec/aacpsy.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/libavcodec/aacpsy.c b/libavcodec/aacpsy.c
> index 78232d4..b16f6b9 100644
> --- a/libavcodec/aacpsy.c
> +++ b/libavcodec/aacpsy.c
> @@ -787,7 +787,7 @@ static void psy_3gpp_analyze_channel(FFPsyContext *ctx, int channel,
>
>              psy_band->threshold = band->thr;
>              psy_band->energy    = band->energy;
> -            psy_band->spread    = spread_en[w+g];
> +            psy_band->spread    = band->active_lines * 2.0f / band_sizes[g];
>          }
>      }


Can't say much since I proposed it myself, so... LGTM ;-)