我正在使用Writingminds FFmpeg在Android上使用FFmpeg。我目前正在尝试从视频中提取帧。
我想从整个视频中均匀分布的视频中提取8帧。我发现这里tutorial是我的实现。
MediaMetadataRetriever retriever = new MediaMetadataRetriever();
retriever.setDataSource(videoCroppedFile.getAbsolutePath());
String time = retriever.extractMetadata(MediaMetadataRetriever.METADATA_KEY_DURATION);
Long videoLength = Long.parseLong(time);
final String cmd[] = {
"-i",
videoCroppedFile.getAbsolutePath(),
"-f",
"image2",
"-ss",
String.valueOf(videoLength.intValue() / ((8 + 1) * 10)),
"-r",
String.valueOf((8 + 1) / videoLength.intValue()),
mediaStorageDir.getAbsolutePath() + "/%d.jpg"
};
但是，当我转到应该保存帧的文件夹时，那里没有任何东西。此外，没有错误消息。
我觉得这是这个库获取String参数的一种方式。我曾经坚持过这个问题，我曾尝试过很多不同版本的cmd。我希望有人可以提供帮助。
这是ffmpeg的输出：
1-22 19:33:14.904 30981-30981/com.firebase.android D/videoFrames: failure reason ffmpeg version n3.0.1 Copyright (c) 2000-2016 the FFmpeg developers
built with gcc 4.8 (GCC)
configuration: --target-os=linux --cross-prefix=/home/vagrant/SourceCode/ffmpeg-android/toolchain-android/bin/arm-linux-androideabi- --arch=arm --cpu=cortex-a8 --enable-runtime-cpudetect --sysroot=/home/vagrant/SourceCode/ffmpeg-android/toolchain-android/sysroot --enable-pic --enable-libx264 --enable-libass --enable-libfreetype --enable-libfribidi --enable-libmp3lame --enable-fontconfig --enable-pthreads --disable-debug --disable-ffserver --enable-version3 --enable-hardcoded-tables --disable-ffplay --disable-ffprobe --enable-gpl --enable-yasm --disable-doc --disable-shared --enable-static --pkg-config=/home/vagrant/SourceCode/ffmpeg-android/ffmpeg-pkg-config --prefix=/home/vagrant/SourceCode/ffmpeg-android/build/armeabi-v7a --extra-cflags='-I/home/vagrant/SourceCode/ffmpeg-android/toolchain-android/include -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 -fno-strict-overflow -fstack-protector-all' --extra-ldflags='-L/home/vagrant/SourceCode/ffmpeg-android/toolchain-android/lib -Wl,-z,relro -Wl,-z,now -pie' --extra-libs='-lpng -lexpat -lm' --extra-cxxflags=
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
libswscale 4. 0.100 / 4. 0.100
libswresample 2. 0.101 / 2. 0.101
libpostproc 54. 0.100 / 54. 0.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/data/user/0/com.firebase.android/cache/videovgntp6q5ar4dglkaflaoobfpcv945824159.mp4':
Metadata:
major_brand : isom
minor_version : 512
compatible_brands: isomiso2avc1mp41
encoder : Lavf57.25.100
Duration: 00:00:08.28, start: 0.000000, bitrate: 391 kb/s
Stream #0:0(eng): Video: h264 (Constrained Baseline) (avc1 / 0x31637661), yuv420p, 720x764 [SAR 1:1 DAR 180:191], 132 kb/s, 16.67 fps, 16.67 tbr, 12800 tbn, 33.33 tbc (default)
Metadata:
handler_name : VideoHandler
Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 256 kb/s (default)
Metadata:
handler_name : SoundHandler
Invalid framerate value: 0
更新2
这是我的Android代码：
try {
ffmpeg.loadBinary(new LoadBinaryResponseHandler() {
@Override
public void onStart() {
Log.d("videoFrames", "starting to load binary");
}
@Override
public void onFailure() {
Log.d("videoFrames", "failed to load binary");
}
@Override
public void onSuccess() {
Log.d("videoFrames", "loaded binary");
try {
ffmpeg.execute(cmd, new ExecuteBinaryResponseHandler() {
@Override
public void onStart() {
Log.d("videoFrames", " starting to get frames from video");
if (mediaStorageDir.isDirectory() && mediaStorageDir.list().length > 0) {
String[] children = mediaStorageDir.list();
for (int i = 0; i < children.length; i++) {
new File(mediaStorageDir, children[i]).delete();
}
}
}
@Override
public void onProgress(String message) {
Log.d("videoFrames", " progress getting frames from video");
}
@Override
public void onFailure(String message) {
Log.d("videoFrames", " failed to get frames from video");
Log.d("videoFrames", " failure reason " + message);
Log.d("videoFrames", " ----------------------------------------------- ");
}
@Override
public void onSuccess(String message) {
Log.d("videoFrames", " success getting frames from video");
}
@Override
public void onFinish() {
Log.d("videoFrames", " finished getting frames from video");
}
});
} catch (FFmpegCommandAlreadyRunningException e) {
Log.d("videoFrames", " command already running in fmpeg");
e.printStackTrace();
}
}
@Override
public void onFinish() {}
});
} catch (FFmpegNotSupportedException e) {
// Handle if FFmpeg is not supported by device
}
更新3
通过执行以下操作修复了我的代码：
final String cmd[] = {
"-i",
videoCroppedFile.getAbsolutePath(),
"-f",
"image2",
"-ss",
String.valueOf(videoLength.floatValue() / (8.0 * 10.0)),
"-r",
String.valueOf(8.0 / videoLength.floatValue()),
mediaStorageDir.getAbsolutePath() + "/%d.jpg"
};