[FFmpeg-devel] [PATCH 17/28] ffmpeg: move the mux queue into muxer private data
Andreas Rheinhardt
andreas.rheinhardt at outlook.com
Thu Jan 13 12:50:48 EET 2022
Anton Khirnov:
> The muxing queue currently lives in OutputStream, which is a very large
> struct storing the state for both encoding and muxing. The muxing queue
> is only used by the code in ffmpeg_mux, so it makes sense to restrict it
> to that file.
>
> This makes the first step towards reducing the scope of OutputStream.
> ---
> fftools/ffmpeg.c | 9 -----
> fftools/ffmpeg.h | 9 -----
> fftools/ffmpeg_mux.c | 91 ++++++++++++++++++++++++++++++++++++--------
> fftools/ffmpeg_opt.c | 6 ---
> 4 files changed, 76 insertions(+), 39 deletions(-)
>
> diff --git a/fftools/ffmpeg.c b/fftools/ffmpeg.c
> index 6c774e9615..c1bb3926c4 100644
> --- a/fftools/ffmpeg.c
> +++ b/fftools/ffmpeg.c
> @@ -595,15 +595,6 @@ static void ffmpeg_cleanup(int ret)
> avcodec_free_context(&ost->enc_ctx);
> avcodec_parameters_free(&ost->ref_par);
>
> - if (ost->muxing_queue) {
> - while (av_fifo_size(ost->muxing_queue)) {
> - AVPacket *pkt;
> - av_fifo_generic_read(ost->muxing_queue, &pkt, sizeof(pkt), NULL);
> - av_packet_free(&pkt);
> - }
> - av_fifo_freep(&ost->muxing_queue);
> - }
> -
> av_freep(&output_streams[i]);
> }
> #if HAVE_THREADS
> diff --git a/fftools/ffmpeg.h b/fftools/ffmpeg.h
> index e828f71dc0..28df1b179f 100644
> --- a/fftools/ffmpeg.h
> +++ b/fftools/ffmpeg.h
> @@ -555,15 +555,6 @@ typedef struct OutputStream {
>
> int max_muxing_queue_size;
>
> - /* the packets are buffered here until the muxer is ready to be initialized */
> - AVFifoBuffer *muxing_queue;
> -
> - /*
> - * The size of the AVPackets' buffers in queue.
> - * Updated when a packet is either pushed or pulled from the queue.
> - */
> - size_t muxing_queue_data_size;
> -
> /* Threshold after which max_muxing_queue_size will be in effect */
> size_t muxing_queue_data_threshold;
>
> diff --git a/fftools/ffmpeg_mux.c b/fftools/ffmpeg_mux.c
> index f4d76e1533..f03202bbb7 100644
> --- a/fftools/ffmpeg_mux.c
> +++ b/fftools/ffmpeg_mux.c
> @@ -32,7 +32,20 @@
> #include "libavformat/avformat.h"
> #include "libavformat/avio.h"
>
> +typedef struct MuxStream {
> + /* the packets are buffered here until the muxer is ready to be initialized */
> + AVFifoBuffer *muxing_queue;
> +
> + /*
> + * The size of the AVPackets' buffers in queue.
> + * Updated when a packet is either pushed or pulled from the queue.
> + */
> + size_t muxing_queue_data_size;
> +} MuxStream;
> +
> struct Muxer {
> + MuxStream *streams;
> +
> /* filesize limit expressed in bytes */
> int64_t limit_filesize;
> int64_t final_filesize;
> @@ -55,6 +68,7 @@ void of_write_packet(OutputFile *of, AVPacket *pkt, OutputStream *ost,
> {
> AVFormatContext *s = of->ctx;
> AVStream *st = ost->st;
> + MuxStream *ms = &of->mux->streams[st->index];
> int ret;
>
> /*
> @@ -76,10 +90,10 @@ void of_write_packet(OutputFile *of, AVPacket *pkt, OutputStream *ost,
> if (!of->mux->header_written) {
> AVPacket *tmp_pkt;
> /* the muxer is not initialized yet, buffer the packet */
> - if (!av_fifo_space(ost->muxing_queue)) {
> - size_t cur_size = av_fifo_size(ost->muxing_queue);
> + if (!av_fifo_space(ms->muxing_queue)) {
> + size_t cur_size = av_fifo_size(ms->muxing_queue);
> unsigned int are_we_over_size =
> - (ost->muxing_queue_data_size + pkt->size) > ost->muxing_queue_data_threshold;
> + (ms->muxing_queue_data_size + pkt->size) > ost->muxing_queue_data_threshold;
> size_t limit = are_we_over_size ? ost->max_muxing_queue_size : INT_MAX;
> size_t new_size = FFMIN(2 * cur_size, limit);
>
> @@ -89,7 +103,7 @@ void of_write_packet(OutputFile *of, AVPacket *pkt, OutputStream *ost,
> ost->file_index, ost->st->index);
> exit_program(1);
> }
> - ret = av_fifo_realloc2(ost->muxing_queue, new_size);
> + ret = av_fifo_realloc2(ms->muxing_queue, new_size);
> if (ret < 0)
> exit_program(1);
> }
> @@ -100,8 +114,8 @@ void of_write_packet(OutputFile *of, AVPacket *pkt, OutputStream *ost,
> if (!tmp_pkt)
> exit_program(1);
> av_packet_move_ref(tmp_pkt, pkt);
> - ost->muxing_queue_data_size += tmp_pkt->size;
> - av_fifo_generic_write(ost->muxing_queue, &tmp_pkt, sizeof(tmp_pkt), NULL);
> + ms->muxing_queue_data_size += tmp_pkt->size;
> + av_fifo_generic_write(ms->muxing_queue, &tmp_pkt, sizeof(tmp_pkt), NULL);
> return;
> }
>
> @@ -283,16 +297,17 @@ int of_check_init(OutputFile *of)
>
> /* flush the muxing queues */
> for (i = 0; i < of->ctx->nb_streams; i++) {
> + MuxStream *ms = &of->mux->streams[i];
> OutputStream *ost = output_streams[of->ost_index + i];
>
> /* try to improve muxing time_base (only possible if nothing has been written yet) */
> - if (!av_fifo_size(ost->muxing_queue))
> + if (!av_fifo_size(ms->muxing_queue))
> ost->mux_timebase = ost->st->time_base;
>
> - while (av_fifo_size(ost->muxing_queue)) {
> + while (av_fifo_size(ms->muxing_queue)) {
> AVPacket *pkt;
> - av_fifo_generic_read(ost->muxing_queue, &pkt, sizeof(pkt), NULL);
> - ost->muxing_queue_data_size -= pkt->size;
> + av_fifo_generic_read(ms->muxing_queue, &pkt, sizeof(pkt), NULL);
> + ms->muxing_queue_data_size -= pkt->size;
> of_write_packet(of, pkt, ost, 1);
> av_packet_free(&pkt);
> }
> @@ -333,6 +348,31 @@ int of_write_trailer(OutputFile *of)
> return 0;
> }
>
> +static void mux_free(Muxer **pmux, int nb_streams)
> +{
> + Muxer *mux = *pmux;
> +
> + if (!mux)
> + return;
> +
> + for (int i = 0; i < nb_streams; i++) {
> + MuxStream *ms = &mux->streams[i];
> +
> + if (!ms->muxing_queue)
> + continue;
> +
> + while (av_fifo_size(ms->muxing_queue)) {
> + AVPacket *pkt;
> + av_fifo_generic_read(ms->muxing_queue, &pkt, sizeof(pkt), NULL);
> + av_packet_free(&pkt);
> + }
> + av_fifo_freep(&ms->muxing_queue);
> + }
> + av_freep(&mux->streams);
> +
> + av_freep(pmux);
> +}
> +
> void of_close(OutputFile **pof)
> {
> OutputFile *of = *pof;
> @@ -342,25 +382,42 @@ void of_close(OutputFile **pof)
> return;
>
> s = of->ctx;
> +
> + mux_free(&of->mux, s ? s->nb_streams : 0);
> +
> if (s && s->oformat && !(s->oformat->flags & AVFMT_NOFILE))
> avio_closep(&s->pb);
> avformat_free_context(s);
> av_dict_free(&of->opts);
>
> - av_freep(&of->mux);
> -
> av_freep(pof);
> }
>
> int of_muxer_init(OutputFile *of, int64_t limit_filesize)
> {
> Muxer *mux = av_mallocz(sizeof(*mux));
> + int ret = 0;
>
> if (!mux)
> return AVERROR(ENOMEM);
>
> + mux->streams = av_calloc(of->ctx->nb_streams, sizeof(*mux->streams));
> + if (!mux->streams) {
> + av_freep(&mux);
> + return AVERROR(ENOMEM);
> + }
> +
> of->mux = mux;
>
> + for (int i = 0; i < of->ctx->nb_streams; i++) {
> + MuxStream *ms = &mux->streams[i];
> + ms->muxing_queue = av_fifo_alloc(8 * sizeof(AVPacket));
> + if (!ms->muxing_queue) {
> + ret = AVERROR(ENOMEM);
> + goto fail;
> + }
> + }
> +
> mux->limit_filesize = limit_filesize;
>
> if (strcmp(of->format->name, "rtp"))
> @@ -368,12 +425,16 @@ int of_muxer_init(OutputFile *of, int64_t limit_filesize)
>
> /* write the header for files with no streams */
> if (of->format->flags & AVFMT_NOSTREAMS && of->ctx->nb_streams == 0) {
> - int ret = of_check_init(of);
> + ret = of_check_init(of);
> if (ret < 0)
> - return ret;
> + goto fail;
> }
>
> - return 0;
> +fail:
> + if (ret < 0)
> + mux_free(&of->mux, of->ctx->nb_streams);
> +
> + return ret;
> }
>
> int of_finished(OutputFile *of)
> diff --git a/fftools/ffmpeg_opt.c b/fftools/ffmpeg_opt.c
> index ed3fd818d0..c7d1d21a37 100644
> --- a/fftools/ffmpeg_opt.c
> +++ b/fftools/ffmpeg_opt.c
> @@ -1613,8 +1613,6 @@ static OutputStream *new_output_stream(OptionsContext *o, AVFormatContext *oc, e
> ost->max_muxing_queue_size = FFMIN(ost->max_muxing_queue_size, INT_MAX / sizeof(ost->pkt));
> ost->max_muxing_queue_size *= sizeof(ost->pkt);
>
> - ost->muxing_queue_data_size = 0;
> -
> ost->muxing_queue_data_threshold = 50*1024*1024;
> MATCH_PER_STREAM_OPT(muxing_queue_data_threshold, i, ost->muxing_queue_data_threshold, oc, st);
>
> @@ -1638,10 +1636,6 @@ static OutputStream *new_output_stream(OptionsContext *o, AVFormatContext *oc, e
> }
> ost->last_mux_dts = AV_NOPTS_VALUE;
>
> - ost->muxing_queue = av_fifo_alloc(8 * sizeof(AVPacket));
> - if (!ost->muxing_queue)
> - exit_program(1);
> -
> return ost;
> }
>
>
My objections to adding a separately allocated muxing context and to
this MuxStream have not changed. Both incur unnecessary allocations and
indirections and (in case of the latter) loops; the latter is also very
unnatural. The patch here actually shows it: You only use the muxer
context to get the MuxStream context corresponding to the OutputStream
you are interested in:
> for (i = 0; i < of->ctx->nb_streams; i++) {
> + MuxStream *ms = &of->mux->streams[i];
> OutputStream *ost = output_streams[of->ost_index + i];
> AVStream *st = ost->st;
> + MuxStream *ms = &of->mux->streams[st->index];
> int ret;
Your aim of making sure what code can use/modify what parts can also be
fulfilled by comments.
- Andreas
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