avconv在14.04从libx264进行管道时抱怨"非单调增加dts到流中复用"

Question

我有一段代码,它采用图像流并使用x264将它们写入文件进行编码和avconv.相关位如下

// Setup encoder
sprintf(cmd, "avconv -i pipe: -vcodec copy %s", filename);
fp = popen(cmd, "w");
x264_param_default_preset(&params, "ultrafast", "stillimage,zerolatency");
params.i_fps_num = fps;
params.i_fps_den = 1;
x264_picture_alloc(&in, X264_CSP_I420, width, height);
params.i_csp = X264_CSP_I420;
in.img.i_csp = X264_CSP_I420;
x.params.b_vfr_input = 0;
in.i_pts = -1;
out.i_pts = -1;
params.i_width = width;
params.i_height = height;
encoder = x264_encoder_open(&params);

in.img.i_plane = 1;
in.img.i_stride[0] = width;
ret = x264_encoder_headers(encoder, &nals, &nheader);
header_size = nals[0].i_payload + nals[1].i_payload + nals[2].i_payload;
fwrite(nals[0].p_payload, header_size, 1, fp);

...
// Loop body
++in.i_pts;
frame_size = x264_encoder_encode(encoder, &nals, &num_nals, &in, &out);
fwrite(nals[0].p_payload, frame_size, 1, fp);

为了清楚起见,我省略了错误检查,但没有返回任何错误.实际上,在我将系统升级到14.04之前,这段代码完美无缺(并且对于尚未升级的同事来说仍然非常有效).

只是现在运行Ubuntu 14.04,我从avconv获得此输出

[h264 @ 0x98dec0] Estimating duration from bitrate, this may be inaccurate
Input #0, h264, from 'pipe:'
  Duration: N/A, bitrate: N/A
    Stream #0.0: Video: h264 (Constrained Baseline), yuv420p, 640x480, 25 fps, 25 tbr, 25 tbn, 60 tbc
Output #0, mp4, to '../reel/test.mp4':
  Metadata:
    encoder         : Lavf54.20.3
    Stream #0.0: Video: libx264, yuv420p, 640x480, q=2-31, 25 tbn, 25 tbc
Stream mapping:
  Stream #0:0 -> #0:0 (copy)
[mp4 @ 0x1347800] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 2 >= 2
av_interleaved_write_frame(): Invalid argument

尽管存在错误,out.i_dts但在视频的整个持续时间内单调增加(总是等于in.i_pts).

我的一般假设是较新版本的avconv对输入流的参数更严格,因此虽然我之前选择的参数可能已经有效,但它们现在不起作用.

可能与之相关的另一个好奇是avconv检测到流是25 FPS,即使x264配置输入FPS为30.

编辑:一些进一步的信息,2>=2无论初始pts(输出dts如预期匹配),都会发生相同的dts error().

Answer 1

在"我不知道为什么要修复它,但确实如此"的时刻,-vcodec copy改为-vcodec libx264(即使源编解码器已经是libx264)修复了dts错误.