Concat 过滤器：初始化输出流时出错答案

【问题标题】：Concat filter: Error initializing output streamConcat 过滤器：初始化输出流时出错
【发布时间】：2020-10-07 17:04:27
【问题描述】：

这是一个后续问题：Flutter (Dart): Merge two videos and view the new output in the device's gallery (photos)

本质上，我正在尝试录制两个视频，将它们合并，然后在图库中查看新视频。我目前在使用 flutter_ffmpeg 包时遇到了一些问题。

我在这里将我的 Flutter 项目上传到 GitHub：

https://github.com/IttaiBarkai/Flutter-Video-Merger

下面是我用来执行ffmpeg的代码的sn-p：

void _videoMerger() async {

    final appDir = await syspaths.getApplicationDocumentsDirectory();
    String rawDocumentPath = appDir.path;
    final outputPath = '$rawDocumentPath/output.mp4';

    final FlutterFFmpeg _flutterFFmpeg = new FlutterFFmpeg();

        String commandToExecute = '-y -i ${_storedVideoOne.path} -i ${_storedVideoTwo.path} -filter_complex \'[0:0][1:0]concat=n=2:v=1:a=0[out]\' -map \'[out]\' $outputPath';
        _flutterFFmpeg.execute(commandToExecute).then((rc) => print("FFmpeg process exited with rc $rc"));

  }

这是执行 ffmpeg 时在我的调试控制台上显示的输出：

D/flutter-ffmpeg(29135): Running FFmpeg with arguments: [-y, -i, /storage/emulated/0/Android/data/com.example.video_merger_two/files/Pictures/1e8947f4-c9c2-4020-b78d-c40fb77ce0d16301015681843175998.mp4, -i, /storage/emulated/0/Android/data/com.example.video_merger_two/files/Pictures/3555b190-a9a6-450d-b6a7-7d1b8fc89ad38627500242651150494.mp4, -filter_complex, [0:0][1:0]concat=n=2:v=1:a=0[out], -map, [out], /data/user/0/com.example.video_merger_two/app_flutter/output.mp4].
    I/mobile-ffmpeg(29135): Loading mobile-ffmpeg.
    I/mobile-ffmpeg(29135): Loaded mobile-ffmpeg-https-x86-4.3.1-20200125.
    D/mobile-ffmpeg(29135): Callback thread started.
    I/mobile-ffmpeg(29135): ffmpeg version git-2020-01-25-fd11dd500
    I/mobile-ffmpeg(29135):  Copyright (c) 2000-2020 the FFmpeg developers
    I/mobile-ffmpeg(29135):
    I/mobile-ffmpeg(29135):   built with Android (5220042 based on r346389c) clang version 8.0.7 (https://android.googlesource.com/toolchain/clang b55f2d4ebfd35bf643d27dbca1bb228957008617) (https://android.googlesource.com/toolchain/llvm 3c393fe7a7e13b0fba4ac75a01aa683d7a5b11cd) (based on LLVM 8.0.7svn)
    I/mobile-ffmpeg(29135):   configuration: --cross-prefix=i686-linux-android- --sysroot=/files/android-sdk/ndk-bundle/toolchains/llvm/prebuilt/linux-x86_64/sysroot --prefix=/home/taner/Projects/mobile-ffmpeg/prebuilt/android-x86/ffmpeg --pkg-config=/usr/bin/pkg-config --enable-version3 --arch=i686 --cpu=i686 --cc=i686-linux-android24-clang --cxx=i686-linux-android24-clang++ --target-os=android --disable-neon --disable-asm --disable-inline-asm --enable-cross-compile --enable-pic --enable-jni --enable-optimizations --enable-swscale --enable-shared --disable-v4l2-m2m --disable-outdev=v4l2 --disable-outdev=fbdev --disable-indev=v4l2 --disable-indev=fbdev --enable-small --disable-openssl --disable-xmm-clobber-test --disable-debug --enable-lto --disable-neon-clobber-test --disable-programs --disable-postproc --disable-doc --disable-htmlpages --disable-manpages --disable-podpages --disable-txtpages --disable-static --disable-sndio --disable-schannel --disable-securetransport --disable-xlib --disable-cuda --disable-cuvid --disable-nvenc --di
    I/mobile-ffmpeg(29135):   libavutil      56. 38.100 / 56. 38.100
    I/mobile-ffmpeg(29135):   libavcodec     58. 65.102 / 58. 65.102
    I/mobile-ffmpeg(29135):   libavformat    58. 35.101 / 58. 35.101
    I/mobile-ffmpeg(29135):   libavdevice    58.  9.103 / 58.  9.103
    I/mobile-ffmpeg(29135):   libavfilter     7. 70.101 /  7. 70.101
    I/mobile-ffmpeg(29135):   libswscale      5.  6.100 /  5.  6.100
    I/mobile-ffmpeg(29135):   libswresample   3.  6.100 /  3.  6.100
    I/mobile-ffmpeg(29135): Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/storage/emulated/0/Android/data/com.example.video_merger_two/files/Pictures/1e8947f4-c9c2-4020-b78d-c40fb77ce0d16301015681843175998.mp4':
    I/mobile-ffmpeg(29135):   Metadata:
    I/mobile-ffmpeg(29135):     major_brand     :
    I/mobile-ffmpeg(29135): mp42
    I/mobile-ffmpeg(29135):
    I/mobile-ffmpeg(29135):     minor_version   :
    I/mobile-ffmpeg(29135): 0
    I/mobile-ffmpeg(29135):
    I/mobile-ffmpeg(29135):     compatible_brands:
    I/mobile-ffmpeg(29135): isommp42
    I/mobile-ffmpeg(29135):
    I/mobile-ffmpeg(29135):     creation_time   :
    I/mobile-ffmpeg(29135): 2020-06-17T18:26:00.000000Z
    I/mobile-ffmpeg(29135):
    I/mobile-ffmpeg(29135):     com.android.version:
    I/mobile-ffmpeg(29135): 10
    I/mobile-ffmpeg(29135):
    I/mobile-ffmpeg(29135):   Duration:
    I/mobile-ffmpeg(29135): 27:34:19.38
    I/mobile-ffmpeg(29135): , start:
    I/mobile-ffmpeg(29135): 0.000000
    I/mobile-ffmpeg(29135): , bitrate:
    I/mobile-ffmpeg(29135): 0 kb/s
    I/mobile-ffmpeg(29135):
    I/mobile-ffmpeg(29135):     Stream #0:0
    I/mobile-ffmpeg(29135): (eng)
    I/mobile-ffmpeg(29135): : Video: h264 (avc1 / 0x31637661), yuv420p(tv, GBR), 1280x720, 3554 kb/s
    I/mobile-ffmpeg(29135): , SAR 1:1 DAR 16:9
    I/mobile-ffmpeg(29135): ,
    I/mobile-ffmpeg(29135): 29.01 fps,
    I/mobile-ffmpeg(29135): 29 tbr,
    I/mobile-ffmpeg(29135): 90k tbn,
    I/mobile-ffmpeg(29135): 180k tbc    
    I/mobile-ffmpeg(29135):  (default)
    I/mobile-ffmpeg(29135):
    I/mobile-ffmpeg(29135):     Metadata:
    I/mobile-ffmpeg(29135):       rotate          :
    I/mobile-ffmpeg(29135): 90
    I/mobile-ffmpeg(29135):
    I/mobile-ffmpeg(29135):       creation_time   :
    I/mobile-ffmpeg(29135): 2020-06-17T18:26:00.000000Z
    I/mobile-ffmpeg(29135):
    I/mobile-ffmpeg(29135):       handler_name    :
    I/mobile-ffmpeg(29135): VideoHandle
    I/mobile-ffmpeg(29135):
    I/mobile-ffmpeg(29135):     Side data:
    I/mobile-ffmpeg(29135):
    I/mobile-ffmpeg(29135): displaymatrix: rotation of -90.00 degrees
    I/mobile-ffmpeg(29135):
    I/mobile-ffmpeg(29135):     Stream #0:1
    I/mobile-ffmpeg(29135): (eng)
    I/mobile-ffmpeg(29135): : Audio: amr_nb (samr / 0x726D6173), 8000 Hz, mono, flt, 12 kb/s
    I/mobile-ffmpeg(29135):  (default)
    I/mobile-ffmpeg(29135):
    I/mobile-ffmpeg(29135):     Metadata:
    I/mobile-ffmpeg(29135):       creation_time   :
    I/mobile-ffmpeg(29135): 2020-06-17T18:26:00.000000Z
    I/mobile-ffmpeg(29135):
    I/mobile-ffmpeg(29135):       handler_name    :
    I/mobile-ffmpeg(29135): SoundHandle
    I/mobile-ffmpeg(29135):
    I/mobile-ffmpeg(29135): Input #1, mov,mp4,m4a,3gp,3g2,mj2, from '/storage/emulated/0/Android/data/com.example.video_merger_two/files/Pictures/3555b190-a9a6-450d-b6a7-7d1b8fc89ad38627500242651150494.mp4':
    I/mobile-ffmpeg(29135):   Metadata:
    I/mobile-ffmpeg(29135):     major_brand     :
    I/mobile-ffmpeg(29135): mp42
    I/mobile-ffmpeg(29135):
    I/mobile-ffmpeg(29135):     minor_version   :
    I/mobile-ffmpeg(29135): 0
    I/mobile-ffmpeg(29135):
    I/mobile-ffmpeg(29135):     compatible_brands:
    I/mobile-ffmpeg(29135): isommp42
    I/mobile-ffmpeg(29135):
    I/mobile-ffmpeg(29135):     creation_time   :
    I/mobile-ffmpeg(29135): 2020-06-17T18:26:09.000000Z
    I/mobile-ffmpeg(29135):
    I/mobile-ffmpeg(29135):     com.android.version:
    I/mobile-ffmpeg(29135): 10
    I/mobile-ffmpeg(29135):
    I/mobile-ffmpeg(29135):   Duration:
    I/mobile-ffmpeg(29135): 27:34:19.62
    I/mobile-ffmpeg(29135): , start:
    I/mobile-ffmpeg(29135): 0.000000
    I/mobile-ffmpeg(29135): , bitrate:
    I/mobile-ffmpeg(29135): 0 kb/s
    I/mobile-ffmpeg(29135):
    I/mobile-ffmpeg(29135):     Stream #1:0
    I/mobile-ffmpeg(29135): (eng)
    I/mobile-ffmpeg(29135): : Video: h264 (avc1 / 0x31637661), yuv420p(tv, GBR), 1280x720, 3765 kb/s
    I/mobile-ffmpeg(29135): , SAR 1:1 DAR 16:9
    I/mobile-ffmpeg(29135): ,
    I/mobile-ffmpeg(29135): 28.80 fps,
    I/mobile-ffmpeg(29135): 29.08 tbr,
    I/mobile-ffmpeg(29135): 90k tbn,
    I/mobile-ffmpeg(29135): 180k tbc
    I/mobile-ffmpeg(29135):  (default)
    I/mobile-ffmpeg(29135):
    I/mobile-ffmpeg(29135):     Metadata:
    I/mobile-ffmpeg(29135):       rotate          :
    I/mobile-ffmpeg(29135): 90
    I/mobile-ffmpeg(29135):
    I/mobile-ffmpeg(29135):       creation_time   :
    I/mobile-ffmpeg(29135): 2020-06-17T18:26:09.000000Z
    I/mobile-ffmpeg(29135):
    I/mobile-ffmpeg(29135):       handler_name    :
    I/mobile-ffmpeg(29135): VideoHandle
    I/mobile-ffmpeg(29135):
    I/mobile-ffmpeg(29135):     Side data:
    I/mobile-ffmpeg(29135):
    I/mobile-ffmpeg(29135): displaymatrix: rotation of -90.00 degrees
    I/mobile-ffmpeg(29135):
    I/mobile-ffmpeg(29135):     Stream #1:1
    I/mobile-ffmpeg(29135): (eng)
    I/mobile-ffmpeg(29135): : Audio: amr_nb (samr / 0x726D6173), 8000 Hz, mono, flt, 12 kb/s
    I/mobile-ffmpeg(29135):  (default)
    I/mobile-ffmpeg(29135):
    I/mobile-ffmpeg(29135):     Metadata:
    I/mobile-ffmpeg(29135):       creation_time   :
    I/mobile-ffmpeg(29135): 2020-06-17T18:26:09.000000Z
    I/mobile-ffmpeg(29135):
    I/mobile-ffmpeg(29135):       handler_name    :
    I/mobile-ffmpeg(29135): SoundHandle
    I/mobile-ffmpeg(29135):
    I/mobile-ffmpeg(29135): Stream mapping:
    I/mobile-ffmpeg(29135):   Stream #0:0 (h264) -> concat:in0:v0
    I/mobile-ffmpeg(29135):
    I/mobile-ffmpeg(29135):   Stream #1:0 (h264) -> concat:in1:v0
    I/mobile-ffmpeg(29135):
    I/mobile-ffmpeg(29135):   concat
    I/mobile-ffmpeg(29135):  -> Stream #0:0 (mpeg4)
    I/mobile-ffmpeg(29135): Press [q] to stop, [?] for help
    W/mobile-ffmpeg(29135): [graph 0 input from stream 0:0 @ 0xed087710] sws_param option is deprecated and ignored
    W/mobile-ffmpeg(29135): [graph 0 input from stream 1:0 @ 0xed086830] sws_param option is deprecated and ignored
    W/mobile-ffmpeg(29135): [mp4 @ 0xeccd8790] Frame rate very high for a muxer not efficiently supporting it.
    W/mobile-ffmpeg(29135): Please consider specifying a lower framerate, a different muxer or -vsync 2
    E/mobile-ffmpeg(29135): [mpeg4 @ 0xe68049d0] timebase 1/1000000 not supported by MPEG 4 standard, the maximum admitted value for the timebase denominator is 65535
    E/mobile-ffmpeg(29135): Error initializing output stream 0:0 -- Error while opening encoder for output stream #0:0 - maybe incorrect parameters such as bit_rate, rate, width or height
    I/mobile-ffmpeg(29135): Conversion failed!
    D/flutter-ffmpeg(29135): FFmpeg exited with rc: 1
    I/flutter (29135): FFmpeg process exited with rc 1

【问题讨论】：

@llogan，感谢您的建议，我现在将进行更改 :)

标签： flutter dart video ffmpeg video-editing

【解决方案1】：

您可能需要稍微不同的过滤器：

-filter_complex "[0:v][1:v]concat=n=2:v=1:a=0[out]" -map "[out]"

其实你可以把这两个输入文件复制到你的电脑上，然后使用命令行调好“真实”的ffmpeg参数，直到结果让你满意为止。只有在那之后，并且在预期的 true 输入文件具有相同特征的情况下，您才能将这些参数放入您的 dart 代码中。

顺便说一句，你是故意把音频流放在这里的吗？

【讨论】：

谢谢，亚历克斯。您建议的过滤器仍然给了我一些错误，但我终于设法弄清楚了。我会在一秒钟内发布我的答案。我真的很感谢你的帮助，关于音频流，我没有意识到我正在放弃它，所以我做了那个改变。再次感谢！！

【解决方案2】：

这是 commandToExecute，它终于为我工作了。希望它可以帮助任何有类似问题的人:)

'-y -i ${_storedVideoOne.path} -i ${_storedVideoTwo.path} -r 24000/1001 -filter_complex \'[0:v:0][0:a:0][1:v:0][1:a:0]concat=n=2:v=1:a=1[out]\' -map \'[out]\' $outputPath'

然后我仍然必须使用以下方法保存最终输出：

 GallerySaver.saveVideo(outputPath).then((_) {});

【讨论】：

好！您需要 GallerySaver（或 another 竞争包）的原因是您希望您的新视频 a) 在系统范围的视频目录中，并且 b) 由 MediaStore 索引。这允许其他应用程序（例如您设备的视频应用程序）找到并播放此视频。
谢谢亚历克斯，这很有道理:)
您好，它产生的视频质量非常低，我怎样才能提高输出文件的质量..有什么想法吗？