[FFmpeg-devel] [PATCH 1/2] lavf: allow BSFs to drop packets.
Ronald S. Bultje
rsbultje at gmail.com
Mon Feb 29 16:32:18 CET 2016
If pkt->size == 0 && pkt->side_data_elems == 0 after bsf->filter()
returns, the packet is considered dropped.
---
ffmpeg.c | 2 ++
libavcodec/avcodec.h | 3 ++-
libavformat/avformat.h | 4 +++-
libavformat/mux.c | 24 +++++++++++++-----------
libavformat/utils.c | 5 +++++
5 files changed, 25 insertions(+), 13 deletions(-)
diff --git a/ffmpeg.c b/ffmpeg.c
index a5ec3c3..8fec1e7 100644
--- a/ffmpeg.c
+++ b/ffmpeg.c
@@ -694,6 +694,8 @@ static void write_frame(AVFormatContext *s, AVPacket *pkt, OutputStream *ost)
if (exit_on_error)
exit_program(1);
}
+ if (pkt->size == 0 && pkt->side_data_elems == 0)
+ return;
if (!(s->oformat->flags & AVFMT_NOTIMESTAMPS)) {
if (pkt->dts != AV_NOPTS_VALUE &&
diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
index d849765..516d236 100644
--- a/libavcodec/avcodec.h
+++ b/libavcodec/avcodec.h
@@ -5208,7 +5208,8 @@ AVBitStreamFilterContext *av_bitstream_filter_init(const char *name);
* If the return value is 0, the output buffer is not allocated and
* should be considered identical to the input buffer, or in case
* *poutbuf was set it points to the input buffer (not necessarily to
- * its starting address).
+ * its starting address). A special case is if *poutbuf was set to NULL and
+ * *poutbuf_size was set to 0, which indicates the packet should be dropped.
*/
int av_bitstream_filter_filter(AVBitStreamFilterContext *bsfc,
AVCodecContext *avctx, const char *args,
diff --git a/libavformat/avformat.h b/libavformat/avformat.h
index 34bad43..a929d96 100644
--- a/libavformat/avformat.h
+++ b/libavformat/avformat.h
@@ -2844,7 +2844,9 @@ int avformat_queue_attached_pictures(AVFormatContext *s);
* Apply a list of bitstream filters to a packet.
*
* @param codec AVCodecContext, usually from an AVStream
- * @param pkt the packet to apply filters to
+ * @param pkt the packet to apply filters to. If, on success, the returned
+ * packet has size == 0 and side_data_elems == 0, it indicates that
+ * the packet should be dropped
* @param bsfc a NULL-terminated list of filters to apply
* @return >=0 on success;
* AVERROR code on failure
diff --git a/libavformat/mux.c b/libavformat/mux.c
index 789c811..5100aa3 100644
--- a/libavformat/mux.c
+++ b/libavformat/mux.c
@@ -1024,6 +1024,19 @@ int av_interleaved_write_frame(AVFormatContext *s, AVPacket *pkt)
if (pkt) {
AVStream *st = s->streams[pkt->stream_index];
+ if (s->oformat->check_bitstream) {
+ if (!st->internal->bitstream_checked) {
+ if ((ret = s->oformat->check_bitstream(s, pkt)) < 0)
+ goto fail;
+ else if (ret == 1)
+ st->internal->bitstream_checked = 1;
+ }
+ }
+
+ av_apply_bitstream_filters(st->codec, pkt, st->internal->bsfc);
+ if (pkt->size == 0 && pkt->side_data_elems == 0)
+ return 0;
+
if (s->debug & FF_FDEBUG_TS)
av_log(s, AV_LOG_TRACE, "av_interleaved_write_frame size:%d dts:%s pts:%s\n",
pkt->size, av_ts2str(pkt->dts), av_ts2str(pkt->pts));
@@ -1037,17 +1050,6 @@ int av_interleaved_write_frame(AVFormatContext *s, AVPacket *pkt)
ret = AVERROR(EINVAL);
goto fail;
}
-
- if (s->oformat->check_bitstream) {
- if (!st->internal->bitstream_checked) {
- if ((ret = s->oformat->check_bitstream(s, pkt)) < 0)
- goto fail;
- else if (ret == 1)
- st->internal->bitstream_checked = 1;
- }
- }
-
- av_apply_bitstream_filters(st->codec, pkt, st->internal->bsfc);
} else {
av_log(s, AV_LOG_TRACE, "av_interleaved_write_frame FLUSH\n");
flush = 1;
diff --git a/libavformat/utils.c b/libavformat/utils.c
index 129a49d..af4695e 100644
--- a/libavformat/utils.c
+++ b/libavformat/utils.c
@@ -4694,6 +4694,11 @@ int av_apply_bitstream_filters(AVCodecContext *codec, AVPacket *pkt,
&new_pkt.data, &new_pkt.size,
pkt->data, pkt->size,
pkt->flags & AV_PKT_FLAG_KEY);
+ if (a == 0 && new_pkt.size == 0 && new_pkt.side_data_elems == 0) {
+ av_packet_unref(pkt);
+ memset(pkt, 0, sizeof(*pkt));
+ return 0;
+ }
if(a == 0 && new_pkt.data != pkt->data) {
uint8_t *t = av_malloc(new_pkt.size + AV_INPUT_BUFFER_PADDING_SIZE); //the new should be a subset of the old so cannot overflow
if (t) {
--
2.1.2
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