我正在尝试使用 FFMPEG 从我的网络摄像头流式传输实时视频/dev/video0。遵循分散的教程和稀缺的文档（这是编码社区的一个已知问题吗？）我得到了以下 bash 脚本：
#!/bin/bash
ffmpeg \
-y \
-f v4l2 \
-i /dev/video0 \
-s 640x480 \
-input_format mjpeg \
-r 24 \
-map 0:0 \
-pix_fmt yuv420p \
-codec:v libvpx \
-s 640x480 \
-threads 4 \
-b:v 50k \
-tile-columns 4 \
-frame-parallel 1 \
-keyint_min 24 -g 24 \
-f webm_chunk \
-header "stream.hdr" \
-chunk_start_index 1 \
stream_%d.chk &
sleep 2
ffmpeg \
-f webm_dash_manifest -live 1 \
-i stream.hdr \
-c copy \
-map 0 \
-f webm_dash_manifest -live 1 \
-adaptation_sets "id=0,streams=0" \
-chunk_start_index 1 \
-chunk_duration_ms 1000 \
-time_shift_buffer_depth 30000 \
-minimum_update_period 60000 \
stream_manifest.mpd
当我运行这个脚本时，我的网络摄像头灯亮起，stream.hdr和stream_manifest.mpd文件被写入，并且开始创建块（即stream_1.chk，stream_2.chk等...）。但是，FFMPEG 会引发以下错误：
无法为输出文件 #0 写入标头（编解码器参数不正确？）：处理输入时发现无效数据
我将解释我认为我在用这个脚本做什么，并希望这会暴露我的想法中的任何错误。
首先，我们调用 FFMPEG 以使用 Video for Linux 2 (v4l2) 从/dev/video0分辨率为 640x480 的网络摄像头 ( ) 中读取数据。输入格式mjpeg的帧率为 24fps。
然后我声明 FFMPEG 应该将 v4l2 输出的视频流“映射”（复制）到一个文件。我指定像素格式（YUV420P）并使用 libvpx（VP8 编码）对视频流进行编码。我将大小设置为 640x480，使用 4 个线程，将比特率设置为 50kbps，使用 tile-columns 和 frame-parallel 选项做一些魔术，并将 I-frames 设置为相隔 24 帧。
然后我创建一个stream.hdr文件。起始索引为 1。此命令继续无限运行，直到我将其杀死，从我的网络摄像头中抓取新视频并将其输出为块。
然后我休眠 2 秒，给前面的命令时间来生成头文件。
就是这样。FFMPEG 的下一次调用只是根据上一步中生成的标头创建 MPEG-DASH 清单文件。
发生什么了？为什么我不能在网络浏览器中观看视频（我使用的是 Dash.js）？我在 Node.js 服务器上提供清单、标头和块，因此琐碎的问题不是问题。
编辑：这是我的完整控制台输出。
ffmpeg version 3.0.7-0ubuntu0.16.10.1 Copyright (c) 2000-2017 the FFmpeg developers
built with gcc 6.2.0 (Ubuntu 6.2.0-5ubuntu12) 20161005
configuration: --prefix=/usr --extra-version=0ubuntu0.16.10.1 --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --cc=cc --cxx=g++ --enable-gpl --enable-shared --disable-stripping --disable-decoder=libopenjpeg --disable-decoder=libschroedinger --enable-avresample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libmodplug --enable-libmp3lame --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-librubberband --enable-librtmp --enable-libschroedinger --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxvid --enable-libzvbi --enable-openal --enable-opengl --enable-x11grab --enable-libdc1394 --enable-libiec61883 --enable-libzmq --enable-frei0r --enable-chromaprint --enable-libx264
libavutil 55. 17.103 / 55. 17.103
libavcodec 57. 24.102 / 57. 24.102
libavformat 57. 25.100 / 57. 25.100
libavdevice 57. 0.101 / 57. 0.101
libavfilter 6. 31.100 / 6. 31.100
libavresample 3. 0. 0 / 3. 0. 0
libswscale 4. 0.100 / 4. 0.100
libswresample 2. 0.101 / 2. 0.101
libpostproc 54. 0.100 / 54. 0.100
[video4linux2,v4l2 @ 0x55847e244ea0] The driver changed the time per frame from 1/24 to 1/30
[mjpeg @ 0x55847e245c00] Changing bps to 8
Input #0, video4linux2,v4l2, from '/dev/video0':
Duration: N/A, start: 64305.102081, bitrate: N/A
Stream #0:0: Video: mjpeg, yuvj422p(pc, bt470bg/unknown/unknown), 640x480, -5 kb/s, 30 fps, 30 tbr, 1000k tbn, 1000k tbc
Codec AVOption frame-parallel (Enable frame parallel decodability features) specified for output file #0 (stream_%d.chk) has not been used for any stream. The most likely reason is either wrong type (e.g. a video option with no video streams) or that it is a private option of some encoder which was not actually used for any stream.
Codec AVOption tile-columns (Number of tile columns to use, log2) specified for output file #0 (stream_%d.chk) has not been used for any stream. The most likely reason is either wrong type (e.g. a video option with no video streams) or that it is a private option of some encoder which was not actually used for any stream.
[swscaler @ 0x55847e24b720] deprecated pixel format used, make sure you did set range correctly
[libvpx @ 0x55847e248a20] v1.5.0
Output #0, webm_chunk, to 'stream_%d.chk':
Metadata:
encoder : Lavf57.25.100
Stream #0:0: Video: vp8 (libvpx), yuv420p, 640x480, q=-1--1, 50 kb/s, 30 fps, 30 tbn, 30 tbc
Metadata:
encoder : Lavc57.24.102 libvpx
Side data:
unknown side data type 10 (24 bytes)
Stream mapping:
Stream #0:0 -> #0:0 (mjpeg (native) -> vp8 (libvpx))
Press [q] to stop, [?] for help
frame= 21 fps=0.0 q=0.0 size=N/A time=00:00:00.70 bitrate=N/A dup=5 drop=frame= 36 fps= 35 q=0.0 size=N/A time=00:00:01.20 bitrate=N/A dup=5 drop=frame= 51 fps= 33 q=0.0 size=N/A time=00:00:01.70 bitrate=N/A dup=5 drop=ffmpeg version 3.0.7-0ubuntu0.16.10.1 Copyright (c) 2000-2017 the FFmpeg developers
built with gcc 6.2.0 (Ubuntu 6.2.0-5ubuntu12) 20161005
configuration: --prefix=/usr --extra-version=0ubuntu0.16.10.1 --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --cc=cc --cxx=g++ --enable-gpl --enable-shared --disable-stripping --disable-decoder=libopenjpeg --disable-decoder=libschroedinger --enable-avresample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libmodplug --enable-libmp3lame --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-librubberband --enable-librtmp --enable-libschroedinger --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxvid --enable-libzvbi --enable-openal --enable-opengl --enable-x11grab --enable-libdc1394 --enable-libiec61883 --enable-libzmq --enable-frei0r --enable-chromaprint --enable-libx264
libavutil 55. 17.103 / 55. 17.103
libavcodec 57. 24.102 / 57. 24.102
libavformat 57. 25.100 / 57. 25.100
libavdevice 57. 0.101 / 57. 0.101
libavfilter 6. 31.100 / 6. 31.100
libavresample 3. 0. 0 / 3. 0. 0
libswscale 4. 0.100 / 4. 0.100
libswresample 2. 0.101 / 2. 0.101
libpostproc 54. 0.100 / 54. 0.100
Input #0, webm_dash_manifest, from 'stream.hdr':
Metadata:
encoder : Lavf57.25.100
Duration: N/A, bitrate: N/A
Stream #0:0: Video: vp8, yuv420p, 640x480, SAR 1:1 DAR 4:3, 30 fps, 30 tbr, 1k tbn, 1k tbc (default)
Metadata:
webm_dash_manifest_file_name: stream.hdr
webm_dash_manifest_track_number: 1
Output #0, webm_dash_manifest, to 'stream_manifest.mpd':
Metadata:
encoder : Lavf57.25.100
Stream #0:0: Video: vp8, yuv420p, 640x480 [SAR 1:1 DAR 4:3], q=2-31, 30 fps, 30 tbr, 1k tbn, 1k tbc (default)
Metadata:
webm_dash_manifest_file_name: stream.hdr
webm_dash_manifest_track_number: 1
Stream mapping:
Stream #0:0 -> #0:0 (copy)
Could not write header for output file #0 (incorrect codec parameters ?): Invalid data found when processing input
frame= 67 fps= 33 q=0.0 size
frame= 82 fps= 32 q=0.0 size=N/A time=00:00:02.73 bitrate=N/A dup=5 drop=
frame= 97 fps= 32 q=0.0 size=N/A time=00:00:03.23 bitrate=N/A dup=5 drop=
frame= 112 fps= 32 q=0.0 size=N/A time=00:00:03.73 bitrate=N/A dup=5 ...