[FFmpeg-devel] [PATCH 1/2] avcodec/libjxldec: add animated decode support

[Anton Khirnov]

Quoting Leo Izen (2023-03-03 21:31:45)
> -static int libjxl_decode_frame(AVCodecContext *avctx, AVFrame *frame, int *got_frame, AVPacket *avpkt)
> +static int libjxl_receive_frame(AVCodecContext *avctx, AVFrame *frame)
>  {
>      LibJxlDecodeContext *ctx = avctx->priv_data;
> -    const uint8_t *buf = avpkt->data;
> -    size_t remaining = avpkt->size;
>      JxlDecoderStatus jret;
>      int ret;
> -    *got_frame = 0;
> +    AVPacket *pkt = ctx->avpkt;
> +
> +    if (!pkt->size) {

Shouldn't this live inside the loop?
It won't happen currently, but in principle ff_decode_get_packet() could
return more than one packet.

> +        av_packet_unref(pkt);
> +        ret = ff_decode_get_packet(avctx, pkt);
> +        if (ret < 0 && ret != AVERROR_EOF)
> +            return ret;
> +        ctx->remaining = pkt->size;
> +        if (!pkt->size) {
> +            /* empty packet means eof */
> +            if (ret >= 0) {
> +                av_packet_unref(pkt);
> +                return AVERROR(EAGAIN);

pkt->size == 0 && ret >= 0
should not happen

> +            } else {
> +                return AVERROR_EOF;
> +            }
> +        }
> +    }
>  
>      while (1) {
>  
> -        jret = JxlDecoderSetInput(ctx->decoder, buf, remaining);
> +        jret = JxlDecoderSetInput(ctx->decoder, pkt->data + (pkt->size - ctx->remaining), ctx->remaining);

Wouldn't it be simpler to offset pkt->data and decremented pkt->size?
Then you shouldn't need ctx->remaining at all.

> @@ -419,25 +471,23 @@ static int libjxl_decode_frame(AVCodecContext *avctx, AVFrame *frame, int *got_f
>                  /* ownership is transfered, and it is not ref-ed */
>                  ctx->iccp = NULL;
>              }
> -            *got_frame = 1;
> -            return avpkt->size - remaining;
> +            frame->pts = av_rescale_q(ctx->pts, ctx->timebase, avctx->pkt_timebase);

I think pkt_timebase does not have to be set.
Also, you should set frame->duration.

-- 
Anton Khirnov