[FFmpeg-devel] [PATCH 5/8] avformat/mux: add proper support for full N:M bitstream filtering

Marton Balint cus at passwd.hu
Sat Mar 28 20:15:12 EET 2020


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) {
+    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)
-- 
2.16.4



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