ffmpeg采集帧出错不退出的补丁

在ffmpeg2.81.11和ffmpeg3.0.7上试验。
ffmpeg没有FFERROR_REDO常量定义，但ffmpeg3.0.7上有。

diff --git a/libavdevice/v4l2.c b/libavdevice/v4l2.c
old mode 100644
new mode 100755
index ddf331d..7b4a826
--- a/libavdevice/v4l2.c
+++ b/libavdevice/v4l2.c
@@ -79,6 +79,7 @@  struct video_data {

     int buffers;
     volatile int buffers_queued;
+    int buffers_ignore;
     void **buf_start;
     unsigned int *buf_len;
     char *standard;
@@ -519,7 +520,9 @@  static int mmap_read_frame(AVFormatContext *ctx, AVPacket *pkt)
         av_log(ctx, AV_LOG_WARNING,
                "Dequeued v4l2 buffer contains corrupted data (%d bytes).\n",
                buf.bytesused);
-        buf.bytesused = 0;
+        s->buffers_ignore = 8;
+        enqueue_buffer(s, &buf);
+        return FFERROR_REDO;
     } else
 #endif
     {
@@ -529,14 +532,28 @@  static int mmap_read_frame(AVFormatContext *ctx, AVPacket *pkt)
             s->frame_size = buf.bytesused;

         if (s->frame_size > 0 && buf.bytesused != s->frame_size) {
-            av_log(ctx, AV_LOG_ERROR,
+            av_log(ctx, AV_LOG_WARNING,
                    "Dequeued v4l2 buffer contains %d bytes, but %d were expected. Flags: 0x%08X.\n",
                    buf.bytesused, s->frame_size, buf.flags);
+            s->buffers_ignore = 8;
             enqueue_buffer(s, &buf);
-            return AVERROR_INVALIDDATA;
+            return FFERROR_REDO;
         }
     }

+
+    /* if we just encounted some corrupted buffers then we ignore the next few
+     * legitimate buffers because they can arrive at irregular intervals, causing
+     * the timestamps of the input and output streams to be out-of-sync and FFmpeg
+     * to continually emit warnings. */
+    if (s->buffers_ignore) {
+        av_log(ctx, AV_LOG_WARNING,
+               "Ignoring dequeued v4l2 buffer due to earlier corruption.\n");
+        s->buffers_ignore --;
+        enqueue_buffer(s, &buf);
+        return FFERROR_REDO;
+    }
+
     /* Image is at s->buff_start[buf.index] */
     if (avpriv_atomic_int_get(&s->buffers_queued) == FFMAX(s->buffers / 8, 1)) {
         /* when we start getting low on queued buffers, fall back on copying data */
@@ -608,6 +625,7 @@  static int mmap_start(AVFormatContext *ctx)
         }
     }
     s->buffers_queued = s->buffers;
+    s->buffers_ignore = 0;

     type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
     if (v4l2_ioctl(s->fd, VIDIOC_STREAMON, &type) < 0) {

参考自https://patchwork.kernel.org/patch/9324933/