[FFmpeg-devel] [PATCH v4 4/8] avformat/mux: add proper support for full N:M bitstream filtering
Marton Balint
cus at passwd.hu
Tue May 5 10:10:18 EEST 2020
On Tue, 5 May 2020, Andreas Rheinhardt wrote:
> 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.
>>
>> This change also allows muxers to set up bitstream filters regardless of the
>> autobsf flag during write_header instead of during check_bitstream and those
>> bitstream filters will always be executed.
>
> Ignoring the autobsf flag is not ok IMO. The muxer should not add a bsf
> when the user explicitly didn't want this.
>
The user should not be allowed to create broken files, and the only way to
achieve that is to force the BSF. I don't see a use case for disabling BSF
either for MXFenc of GXFenc. (in fact, from the top of my head I can't
see a use case for disabling automatically inserted BSF-s in other
muxers).
So if you feel strongly about this and we still want to avoid creating
corrupt files then the BSFs should be processed in mxf_interleave and
gxf_interleave separately from the auto inserted bitstream filters. Do you
think that is better? I don't think so.
Regards,
Marton
> - Andreas
>
>>
>> Signed-off-by: Marton Balint <cus at passwd.hu>
>> ---
>> libavformat/mux.c | 87 +++++++++++++++++++++++++++++++++++--------------------
>> 1 file changed, 56 insertions(+), 31 deletions(-)
>>
>> diff --git a/libavformat/mux.c b/libavformat/mux.c
>> index 33aed9da90..d3a98499ce 100644
>> --- a/libavformat/mux.c
>> +++ b/libavformat/mux.c
>> @@ -1077,8 +1077,8 @@ static int interleave_packet(AVFormatContext *s, AVPacket *out, AVPacket *in, in
>> return ff_interleave_packet_per_dts(s, out, in, flush);
>> }
>>
>> -static int do_packet_auto_bsf(AVFormatContext *s, AVPacket *pkt) {
>> - AVStream *st = s->streams[pkt->stream_index];
>> +static int check_bitstream(AVFormatContext *s, AVStream *st, AVPacket *pkt)
>> +{
>> int ret;
>>
>> if (!(s->flags & AVFMT_FLAG_AUTO_BSF))
>> @@ -1093,30 +1093,6 @@ static int do_packet_auto_bsf(AVFormatContext *s, AVPacket *pkt) {
>> }
>> }
>>
>> - if (st->internal->bsfc) {
>> - AVBSFContext *ctx = st->internal->bsfc;
>> - // 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;
>> }
>>
>> @@ -1161,17 +1137,53 @@ static int write_packet_common(AVFormatContext *s, AVStream *st, AVPacket *pkt,
>> }
>> }
>>
>> +static int write_packets_from_bsfs(AVFormatContext *s, AVStream *st, AVPacket *pkt, int interleaved)
>> +{
>> + AVBSFContext *bsfc = st->internal->bsfc;
>> + int ret;
>> +
>> + if ((ret = av_bsf_send_packet(bsfc, pkt)) < 0) {
>> + av_log(s, AV_LOG_ERROR,
>> + "Failed to send packet to filter %s for stream %d\n",
>> + bsfc->filter->name, st->index);
>> + return ret;
>> + }
>> +
>> + do {
>> + ret = av_bsf_receive_packet(bsfc, pkt);
>> + if (ret < 0) {
>> + if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
>> + return 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 != AVERROR(ENOMEM))
>> + continue;
>> + return ret;
>> + }
>> + av_packet_rescale_ts(pkt, bsfc->time_base_out, st->time_base);
>> + ret = write_packet_common(s, st, pkt, interleaved);
>> + if (ret >= 0 && !interleaved) // a successful write_packet_common already unrefed pkt for interleaved
>> + av_packet_unref(pkt);
>> + } while (ret >= 0);
>> +
>> + return ret;
>> +}
>> +
>> static int write_packets_common(AVFormatContext *s, AVStream *st, AVPacket *pkt, int interleaved)
>> {
>> int ret = prepare_input_packet(s, pkt);
>> if (ret < 0)
>> return ret;
>>
>> - ret = do_packet_auto_bsf(s, pkt);
>> - if (ret <= 0)
>> + ret = check_bitstream(s, st, pkt);
>> + if (ret < 0)
>> return ret;
>>
>> - return write_packet_common(s, st, pkt, interleaved);
>> + if (st->internal->bsfc) {
>> + return write_packets_from_bsfs(s, st, pkt, interleaved);
>> + } else {
>> + return write_packet_common(s, st, pkt, interleaved);
>> + }
>> }
>>
>> int av_write_frame(AVFormatContext *s, AVPacket *in)
>> @@ -1238,9 +1250,22 @@ int av_interleaved_write_frame(AVFormatContext *s, AVPacket *pkt)
>>
>> int av_write_trailer(AVFormatContext *s)
>> {
>> - int ret, i;
>> + int i, ret1, ret = 0;
>> + AVPacket pkt = {0};
>> + av_init_packet(&pkt);
>>
>> - ret = interleaved_write_packet(s, NULL, 1);
>> + for (i = 0; i < s->nb_streams; i++) {
>> + if (s->streams[i]->internal->bsfc) {
>> + ret1 = write_packets_from_bsfs(s, s->streams[i], &pkt, 1/*interleaved*/);
>> + if (ret1 < 0)
>> + av_packet_unref(&pkt);
>> + 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)
>>
>
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