[FFmpeg-devel] [PATCH] libavcodec/libfdk-aacnc: send encoder delay/padding in packet side data
Martin Storsjö
martin at martin.st
Tue Feb 28 14:18:38 EET 2023
On Fri, 24 Feb 2023, JonHGee wrote:
> ---
> libavcodec/libfdk-aacenc.c | 27 ++++++++++++++++++++++++++-
> 1 file changed, 26 insertions(+), 1 deletion(-)
>
> diff --git a/libavcodec/libfdk-aacenc.c b/libavcodec/libfdk-aacenc.c
> index 54549de473..55d10990e4 100644
> --- a/libavcodec/libfdk-aacenc.c
> +++ b/libavcodec/libfdk-aacenc.c
> @@ -21,6 +21,7 @@
>
> #include "libavutil/channel_layout.h"
> #include "libavutil/common.h"
> +#include "libavutil/intreadwrite.h"
> #include "libavutil/opt.h"
> #include "avcodec.h"
> #include "audio_frame_queue.h"
> @@ -46,6 +47,7 @@ typedef struct AACContext {
> int latm;
> int header_period;
> int vbr;
> + int delay_sent;
>
> AudioFrameQueue afq;
> } AACContext;
> @@ -368,7 +370,7 @@ static int aac_encode_frame(AVCodecContext *avctx, AVPacket *avpkt,
> int out_buffer_identifier = OUT_BITSTREAM_DATA;
> int out_buffer_size, out_buffer_element_size;
> void *in_ptr, *out_ptr;
> - int ret;
> + int ret, discard_padding;
> uint8_t dummy_buf[1];
> AACENC_ERROR err;
>
> @@ -428,6 +430,29 @@ static int aac_encode_frame(AVCodecContext *avctx, AVPacket *avpkt,
> ff_af_queue_remove(&s->afq, avctx->frame_size, &avpkt->pts,
> &avpkt->duration);
>
> + discard_padding = avctx->frame_size - avpkt->duration;
> + // Check if subtraction resulted in an overflow
> + if ((discard_padding < avctx->frame_size) != (avpkt->duration > 0)) {
> + av_log(avctx, AV_LOG_ERROR, "discard padding overflow\n");
> + av_packet_unref(avpkt);
> + av_free(avpkt);
I don't think we can or should free the avpkt pointer here (which is
allocated by the caller).
> + return AVERROR(EINVAL);
> + }
> + if ((!s->delay_sent && avctx->initial_padding > 0) || discard_padding > 0) {
> + uint8_t *side_data =
> + av_packet_new_side_data(avpkt, AV_PKT_DATA_SKIP_SAMPLES, 10);
> + if (!side_data) {
> + av_packet_unref(avpkt);
> + av_free(avpkt);
> + return AVERROR(ENOMEM);
> + }
> + if (!s->delay_sent) {
> + AV_WL32(side_data, avctx->initial_padding);
> + s->delay_sent = 1;
> + }
> + AV_WL32(side_data + 4, discard_padding);
> + }
> +
Other than that, this seems reasonable. There's a bunch of stylistic
choices that I'd do slightly differently here, but this seems to match
existing code in libavcodec/libmp3lame.c, so it's probably ok to keep it
matching.
// Martin
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