ffmpeg 0.10.3 h264_mp4toannexb 异常

在使用

ffmpeg -i test.mp4 -ss 0 -t 10 -acodec copy -vcodec copy -vbsf h264_mp4toannexb -y test.ts

命令的时候， 部分视频会出现异常：

Failed to open bitstream filter h264_mp4toannexb for stream 0 with codec copy: Invalid argument
Failed to open bitstream filter h264_mp4toannexb for stream 0 with codec copy: Invalid argument
Failed to open bitstream filter h264_mp4toannexb for stream 0 with codec copy: Invalid argument
Failed to open bitstream filter h264_mp4toannexb for stream 0 with codec copy: Invalid argument
Failed to open bitstream filter h264_mp4toannexb for stream 0 with codec copy: Invalid argument
[mpegts @ 0x14eb0980] H.264 bitstream malformed, no startcode found, use the h264_mp4toannexb bitstream filter
av_interleaved_write_frame(): Invalid data found when processing input

需要调整

libavcodec/h264_mp4toannexb_bsf.c

解决。

调整为：

        /* retrieve length coded size */        ctx->length_size = (*extradata++ & 0x3) + 1;//@alex//        if (ctx->length_size == 3)//            return AVERROR(EINVAL);

以及：

    *poutbuf_size = 0;    *poutbuf = NULL;    do {        ret= AVERROR(EINVAL);        if (buf + ctx->length_size > buf_end)            goto fail;        if (ctx->length_size == 1) {            nal_size = buf[0];        } else if (ctx->length_size == 2) {            nal_size = AV_RB16(buf);//@alex//        } else//            nal_size = AV_RB32(buf);} else { for(nal_size = 0, unit_type = 0; unit_type < ctx->length_size; unit_type++)nal_size = (nal_size << 8) | buf[unit_type]; }

参考：

http://ffmpeg-users.933282.n4.nabble.com/MPEG-TS-trouble-td4491337.html

there is a bug in libavcodec/h264_mp4toannexb_bsf.c
when the ctx->length_size == 3 , the filter will report the error
"Invalid argument"

diff --git a/libavcodec/h264_mp4toannexb_bsf.c
b/libavcodec/h264_mp4toannexb_bsf.c
index 5085ecb..fa16f2a 100644
--- a/libavcodec/h264_mp4toannexb_bsf.c
+++ b/libavcodec/h264_mp4toannexb_bsf.c
@@ -82,8 +82,8 @@ static int
h264_mp4toannexb_filter(AVBitStreamFilterContext *bsfc,
 
         /* retrieve length coded size */
         ctx->length_size = (*extradata++ & 0x3) + 1;
-        if (ctx->length_size == 3)
-            return AVERROR(EINVAL);
+    //    if (ctx->length_size == 3)
+    //        return AVERROR(EINVAL);
 
         /* retrieve sps and pps unit(s) */
         unit_nb = *extradata++ & 0x1f; /* number of sps unit(s) */
@@ -146,8 +146,10 @@ pps:
             nal_size = buf[0];
         } else if (ctx->length_size == 2) {
             nal_size = AV_RB16(buf);
-        } else
-            nal_size = AV_RB32(buf);
+        } else {
+            for(nal_size = 0, unit_type = 0;
unit_type<ctx->length_size; unit_type++)
+                nal_size =  (nal_size << 8) | buf[unit_type];
+        }
 
         buf += ctx->length_size;
         unit_type = *buf & 0x1f;