[FFmpeg-devel] [PATCH] dsddec: correct for DSD silence bit-ordering

[Paul B Mahol]

On 3/31/17, Takayuki 'January June' Suwa <jjsuwa.sys3175 at gmail.com> wrote:
> ---
>  libavcodec/dsddec.c | 17 ++++++++++-------
>  1 file changed, 10 insertions(+), 7 deletions(-)
>
> diff --git a/libavcodec/dsddec.c b/libavcodec/dsddec.c
> index 880d691..2c5c357 100644
> --- a/libavcodec/dsddec.c
> +++ b/libavcodec/dsddec.c
> @@ -31,10 +31,18 @@
>  #include "avcodec.h"
>  #include "dsd.h"
>
> +#define DSD_SILENCE 0x69
> +/* 0x69 = 01101001
> + * This pattern "on repeat" makes a low energy 352.8 kHz tone
> + * and a high energy 1.0584 MHz tone which should be filtered
> + * out completely by any playback system --> silence
> + */
> +
>  static av_cold int decode_init(AVCodecContext *avctx)
>  {
>      DSDContext * s;
>      int i;
> +    uint8_t silence;
>
>      ff_init_dsd_data();
>
> @@ -42,15 +50,10 @@ 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 ? ff_reverse[DSD_SILENCE] : DSD_SILENCE;
>      for (i = 0; i < avctx->channels; i++) {
>          s[i].pos = 0;
> -        memset(s[i].buf, 0x69, sizeof(s[i].buf));
> -
> -        /* 0x69 = 01101001
> -         * This pattern "on repeat" makes a low energy 352.8 kHz tone
> -         * and a high energy 1.0584 MHz tone which should be filtered
> -         * out completely by any playback system --> silence
> -         */
> +        memset(s[i].buf, silence, sizeof(s[i].buf));
>      }
>
>      avctx->sample_fmt = AV_SAMPLE_FMT_FLTP;
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>

lgtm