On Tue, Aug 31, 2021 at 2:44 PM Andreas Rheinhardt
<andreas.rheinha...@outlook.com> wrote:
>
> Currently the APTX (HD) codecs set frame_size if unset and check
> whether it is divisible by block_size (corresponding to block_align
> as used by other codecs). But this is based upon a misunderstanding
> of the API: frame_size is not in bytes, but in samples.*
>
> Said value is also not intended to be set by the user at all,
> but set by encoders and (possibly) decoders if the number of channels
> in a frame is constant. The latter condition is not fulfilled here,
> so only set it for encoders to the value that it already had for APTX:
> 1024 samples (per channel).
>
> *: If it were needed to check said value, one would need to check
> for it to be divisible by four (four samples correspond to one block
> of block_size bytes).
>
> Signed-off-by: Andreas Rheinhardt <andreas.rheinha...@outlook.com>
> ---
> libavcodec/aptx.c | 10 ++--------
> 1 file changed, 2 insertions(+), 8 deletions(-)
>
> diff --git a/libavcodec/aptx.c b/libavcodec/aptx.c
> index 3aeee1907c..97397aca68 100644
> --- a/libavcodec/aptx.c
> +++ b/libavcodec/aptx.c
> @@ -515,14 +515,8 @@ av_cold int ff_aptx_init(AVCodecContext *avctx)
> s->hd = avctx->codec->id == AV_CODEC_ID_APTX_HD;
> s->block_size = s->hd ? 6 : 4;
>
> - if (avctx->frame_size == 0)
> - avctx->frame_size = 256 * s->block_size;
> -
> - if (avctx->frame_size % s->block_size) {
> - av_log(avctx, AV_LOG_ERROR,
> - "Frame size must be a multiple of %d samples\n",
> s->block_size);
> - return AVERROR(EINVAL);
> - }
> + if (av_codec_is_encoder(avctx->codec))
> + avctx->frame_size = 1024;
>
s->block_size can be 6 for HD or 4 for non-HD, making the default
frame_size not always 1024 before this change, thus a change in
behavior for aptx HD. Is this intended?
- Hendrik
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