examples/muxing: Don't use stack packet

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

doc/examples/muxing.c

@@ -62,6 +62,8 @@ typedef struct OutputStream {
     AVFrame *frame;
     AVFrame *tmp_frame;
 
+    AVPacket *tmp_pkt;
+
     float t, tincr, tincr2;
 
     struct SwsContext *sws_ctx;
@@ -80,7 +82,7 @@ static void log_packet(const AVFormatContext *fmt_ctx, const AVPacket *pkt)
 }
 
 static int write_frame(AVFormatContext *fmt_ctx, AVCodecContext *c,
-                       AVStream *st, AVFrame *frame)
+                       AVStream *st, AVFrame *frame, AVPacket *pkt)
 {
     int ret;
 
@@ -93,9 +95,7 @@ static int write_frame(AVFormatContext *fmt_ctx, AVCodecContext *c,
     }
 
     while (ret >= 0) {
-        AVPacket pkt = { 0 };
-
-        ret = avcodec_receive_packet(c, &pkt);
+        ret = avcodec_receive_packet(c, pkt);
         if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
             break;
         else if (ret < 0) {
@@ -104,12 +104,12 @@ static int write_frame(AVFormatContext *fmt_ctx, AVCodecContext *c,
         }
 
         /* rescale output packet timestamp values from codec to stream timebase */
-        av_packet_rescale_ts(&pkt, c->time_base, st->time_base);
-        pkt.stream_index = st->index;
+        av_packet_rescale_ts(pkt, c->time_base, st->time_base);
+        pkt->stream_index = st->index;
 
         /* Write the compressed frame to the media file. */
-        log_packet(fmt_ctx, &pkt);
-        ret = av_interleaved_write_frame(fmt_ctx, &pkt);
+        log_packet(fmt_ctx, pkt);
+        ret = av_interleaved_write_frame(fmt_ctx, pkt);
         /* pkt is now blank (av_interleaved_write_frame() takes ownership of
          * its contents and resets pkt), so that no unreferencing is necessary.
          * This would be different if one used av_write_frame(). */
@@ -138,6 +138,12 @@ static void add_stream(OutputStream *ost, AVFormatContext *oc,
         exit(1);
     }
 
+    ost->tmp_pkt = av_packet_alloc();
+    if (!ost->tmp_pkt) {
+        fprintf(stderr, "Could not allocate AVPacket\n");
+        exit(1);
+    }
+
     ost->st = avformat_new_stream(oc, NULL);
     if (!ost->st) {
         fprintf(stderr, "Could not allocate stream\n");
@@ -380,7 +386,7 @@ static int write_audio_frame(AVFormatContext *oc, OutputStream *ost)
         ost->samples_count += dst_nb_samples;
     }
 
-    return write_frame(oc, c, ost->st, frame);
+    return write_frame(oc, c, ost->st, frame, ost->tmp_pkt);
 }
 
 /**************************************************************/
@@ -523,7 +529,7 @@ static AVFrame *get_video_frame(OutputStream *ost)
  */
 static int write_video_frame(AVFormatContext *oc, OutputStream *ost)
 {
-    return write_frame(oc, ost->enc, ost->st, get_video_frame(ost));
+    return write_frame(oc, ost->enc, ost->st, get_video_frame(ost), ost->tmp_pkt);
 }
 
 static void close_stream(AVFormatContext *oc, OutputStream *ost)
@@ -531,6 +537,7 @@ static void close_stream(AVFormatContext *oc, OutputStream *ost)
     avcodec_free_context(&ost->enc);
     av_frame_free(&ost->frame);
     av_frame_free(&ost->tmp_frame);
+    av_packet_free(&ost->tmp_pkt);
     sws_freeContext(ost->sws_ctx);
     swr_free(&ost->swr_ctx);
 }