Re: [FFmpeg-devel] [PATCH 5/7] avcodec/dsddec: Fix decoding LSBF samples

From: Peter Ross <pross@xvid.org>
To: FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org>
Subject: Re: [FFmpeg-devel] [PATCH 5/7] avcodec/dsddec: Fix decoding LSBF samples
Date: Tue, 2 Apr 2024 18:21:54 +1100
Message-ID: <ZguyErl7U7V5dPAs@a5376560c12b271e484bce3a31b3134b> (raw)
In-Reply-To: <GV1P250MB0737E070BC3631C474478FED8F3E2@GV1P250MB0737.EURP250.PROD.OUTLOOK.COM>

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On Tue, Apr 02, 2024 at 03:37:06AM +0200, Andreas Rheinhardt wrote:
> ff_dsd2pcm_translate() works internally by converting LSBF input
> to MSBF upon reading; its buffer is therefore always MSBF
> and should therefore be initialized with MSBF silence;
> but this is not true since e3d8963c3cb5b8cd31460dd9b3b9dba2a2343bf5
> which this patch effectively reverts.
> 
> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
> ---
>  libavcodec/dsddec.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/libavcodec/dsddec.c b/libavcodec/dsddec.c
> index 22009c70ef..2bb2e73b75 100644
> --- a/libavcodec/dsddec.c
> +++ b/libavcodec/dsddec.c
> @@ -56,7 +56,7 @@ static av_cold int decode_init(AVCodecContext *avctx)
>      if (!s)
>          return AVERROR(ENOMEM);
>  
> -    silence = avctx->codec_id == AV_CODEC_ID_DSD_LSBF || avctx->codec_id == AV_CODEC_ID_DSD_LSBF_PLANAR ? DSD_SILENCE_REVERSED : DSD_SILENCE;
> +    silence = DSD_SILENCE;
>      for (i = 0; i < avctx->ch_layout.nb_channels; i++) {
>          s[i].pos = 0;
>          memset(s[i].buf, silence, sizeof(s[i].buf));
> -- 

ok.

with this patch, DSD_SILENCE, DSD_SILENCE_REVERSED macros and even the silence
var are no longer neccessary.

i suggest reverting the memset line and attached comment back to way it was in
the initial commit (5f4f9ee99f4e9ab980bb18475009c701ba47a74f).

-- Peter
(A907 E02F A6E5 0CD2 34CD 20D2 6760 79C5 AC40 DD6B)

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