[FFmpeg-devel] [PATCH 5/8] avformat/mux: add proper support for full N:M bitstream filtering
Andreas Rheinhardt
andreas.rheinhardt at gmail.com
Tue Mar 31 16:35:29 EEST 2020
Marton Balint:
> Previously only 1:1 bitstream filters were supported, the end of the stream was
> not signalled to the bitstream filters and time base changes were ignored.
>
> Signed-off-by: Marton Balint <cus at passwd.hu>
> ---
> libavformat/internal.h | 1 +
> libavformat/mux.c | 128 ++++++++++++++++++++++++++++++++++---------------
> 2 files changed, 91 insertions(+), 38 deletions(-)
>
> diff --git a/libavformat/internal.h b/libavformat/internal.h
> index 332477a532..45aeef717a 100644
> --- a/libavformat/internal.h
> +++ b/libavformat/internal.h
> @@ -158,6 +158,7 @@ struct AVStreamInternal {
> */
> AVBSFContext **bsfcs;
> int nb_bsfcs;
> + int bsfcs_idx;
>
> /**
> * Whether or not check_bitstream should still be run on each packet
> diff --git a/libavformat/mux.c b/libavformat/mux.c
> index 8c2d6a8060..3054ab8644 100644
> --- a/libavformat/mux.c
> +++ b/libavformat/mux.c
> @@ -840,14 +840,48 @@ static int prepare_input_packet(AVFormatContext *s, AVPacket *pkt)
> return 0;
> }
>
> -static int do_packet_auto_bsf(AVFormatContext *s, AVPacket *pkt) {
> - AVStream *st = s->streams[pkt->stream_index];
> - int i, ret;
> +static int auto_bsf_receive_packet(AVFormatContext *s, AVStream *st, AVPacket *pkt)
> +{
> + AVStreamInternal *sti = st->internal;
> + int ret = AVERROR(EAGAIN);
> + int eof = 0;
> +
> + while (sti->bsfcs_idx) {
> + /* get a packet from the previous filter up the chain */
> + ret = av_bsf_receive_packet(sti->bsfcs[sti->bsfcs_idx - 1], pkt);
> + if (ret == AVERROR(EAGAIN)) {
> + sti->bsfcs_idx--;
> + continue;
> + } else if (ret == AVERROR_EOF) {
> + eof = 1;
> + } else if (ret < 0)
> + break;
> +
> + /* send it to the next filter down the chain */
> + if (sti->bsfcs_idx < sti->nb_bsfcs) {
> + ret = av_bsf_send_packet(sti->bsfcs[sti->bsfcs_idx], eof ? NULL : pkt);
> + av_assert2(ret != AVERROR(EAGAIN));
> + if (ret < 0)
> + break;
> + sti->bsfcs_idx++;
> + eof = 0;
> + } else if (eof) {
> + break;
> + } else {
> + return 0;
> + }
> + }
> +
> + return ret;
> +}
> +
> +static int need_auto_bsf(AVFormatContext *s, AVStream *st, AVPacket *pkt) {
{ belongs into a line of its own.
> + int ret;
>
> if (!(s->flags & AVFMT_FLAG_AUTO_BSF))
> - return 1;
> + return 0;
>
> - if (s->oformat->check_bitstream) {
> + if (pkt && s->oformat->check_bitstream) {
> if (!st->internal->bitstream_checked) {
> if ((ret = s->oformat->check_bitstream(s, pkt)) < 0)
> return ret;
> @@ -856,31 +890,7 @@ static int do_packet_auto_bsf(AVFormatContext *s, AVPacket *pkt) {
> }
> }
>
> - for (i = 0; i < st->internal->nb_bsfcs; i++) {
> - AVBSFContext *ctx = st->internal->bsfcs[i];
> - // TODO: when any bitstream filter requires flushing at EOF, we'll need to
> - // flush each stream's BSF chain on write_trailer.
> - if ((ret = av_bsf_send_packet(ctx, pkt)) < 0) {
> - av_log(ctx, AV_LOG_ERROR,
> - "Failed to send packet to filter %s for stream %d\n",
> - ctx->filter->name, pkt->stream_index);
> - return ret;
> - }
> - // TODO: when any automatically-added bitstream filter is generating multiple
> - // output packets for a single input one, we'll need to call this in a loop
> - // and write each output packet.
> - if ((ret = av_bsf_receive_packet(ctx, pkt)) < 0) {
> - if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
> - return 0;
> - av_log(ctx, AV_LOG_ERROR,
> - "Failed to receive packet from filter %s for stream %d\n",
> - ctx->filter->name, pkt->stream_index);
> - if (s->error_recognition & AV_EF_EXPLODE)
> - return ret;
> - return 0;
> - }
> - }
> - return 1;
> + return st->internal->nb_bsfcs;
> }
>
> static int interleaved_write_packet(AVFormatContext *s, AVPacket *pkt, int flush);
> @@ -909,19 +919,54 @@ static int write_packet_common(AVFormatContext *s, AVStream *st, AVPacket *pkt,
>
> static int write_packets_common(AVFormatContext *s, AVStream *st, AVPacket *pkt, int interleaved)
> {
> - int ret = do_packet_auto_bsf(s, pkt);
> - if (ret == 0)
> - return 0;
> - else if (ret < 0)
> + AVStreamInternal *sti = st->internal;
> + int ret;
> +
> + ret = need_auto_bsf(s, st, pkt);
> + if (ret < 0)
> goto fail;
>
> - ret = write_packet_common(s, st, pkt, interleaved);
> + if (ret) {
> + AVPacket opkt = {0};
> + int consumed_packet = 0;
> +
> + do {
> + ret = auto_bsf_receive_packet(s, st, &opkt);
> + if (ret < 0) {
> + if (ret == AVERROR(EAGAIN) && !consumed_packet) {
> + av_assert2(sti->bsfcs_idx == 0);
> + ret = av_bsf_send_packet(sti->bsfcs[0], pkt);
> + av_assert2(ret != AVERROR(EAGAIN));
> + if (ret >= 0) {
> + consumed_packet = 1;
> + sti->bsfcs_idx = 1;
> + continue;
> + }
> + }
> + if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
> + ret = 0;
> + if (ret < 0) {
> + av_log(s, AV_LOG_ERROR, "Error applying bitstream filters to an output "
> + "packet for stream #%d: %s\n", st->index, av_err2str(ret));
> + if (!(s->error_recognition & AV_EF_EXPLODE))
> + ret = 0;
> + }
> + goto fail;
> + }
> + av_packet_rescale_ts(&opkt, sti->bsfcs[sti->nb_bsfcs-1]->time_base_out, st->time_base);
> + ret = write_packet_common(s, st, &opkt, interleaved);
> + if (!interleaved)
> + av_packet_unref(&opkt);
> + } while (ret >= 0);
> + } else {
> + ret = pkt ? write_packet_common(s, st, pkt, interleaved) : 0;
> + }
> if (ret < 0)
> goto fail;
> return ret;
>
> fail:
> - if (interleaved)
> + if (interleaved && pkt)
> av_packet_unref(pkt);
> return ret;
> }
> @@ -1264,9 +1309,16 @@ fail:
>
> int av_write_trailer(AVFormatContext *s)
> {
> - int ret, i;
> + int i, ret1, ret = 0;
>
> - ret = interleaved_write_packet(s, NULL, 1);
> + for (i = 0; i < s->nb_streams; i++) {
> + ret1 = write_packets_common(s, s->streams[i], NULL, 1/*interleaved*/);
> + if (ret >= 0)
> + ret = ret1;
> + }
> + ret1 = interleaved_write_packet(s, NULL, 1);
> + if (ret >= 0)
> + ret = ret1;
>
> if (s->oformat->write_trailer) {
> if (!(s->oformat->flags & AVFMT_NOFILE) && s->pb)
>
I'm not fully done yet, but I already suggest the following changes:
1. Factor out the bitstream filter stuff (I mean what is after the if
(ret) in write_packets_common()) into a separate function.
2. Don't call write_packets_common() from av_write_trailer(); instead
simply do if (s->streams[i]->internal->nb_bsfs) ret1 = the function from 1.
This will already make sure that write_packets_common() is only called
when there is a packet, so that all of these checks for whether there is
a packet can be removed. Furthermore, this allows to include
prepare_input_packet() in write_packets_common().
- Andreas
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