java - Android FFmpegMediaMetadataRetriever.getFrameAtTime() 很慢

Question

我正在开发一个应用程序，该应用程序最终将以 200 毫秒的间隔将视频切割成帧。

该应用程序可以工作，您选择一个视频，该应用程序会将其切割成存储在设备上的位图。问题是，FFmpegMediaMetaRetriever.getFrameAtTime() 非常慢。我的意思是，处理视频所需的时间比视频长度本身要长，我看到平均每帧大约 1.1 秒。

我已经跟踪到调用 getFrameAtTime 的延迟。还有其他人知道在特定时间从视频中获取帧的更好方法吗？

代码:

    new Thread(new Runnable() {
        @Override
        public void run() {
            FFmpegMediaMetadataRetriever retriever = new FFmpegMediaMetadataRetriever();
            retriever.setDataSource(getPath(EditVideo.this, mMediaUri));
            String time = retriever.extractMetadata(FFmpegMediaMetadataRetriever.METADATA_KEY_DURATION);

            // FFmpegMediaMetadataRetriever doesn't have the ability to get Width and Height of video, needed to scale down to 1024.
            MediaMetadataRetriever retriever1 = new MediaMetadataRetriever();
            retriever1.setDataSource(getPath(EditVideo.this, mMediaUri));
            int width = Integer.parseInt(retriever1.extractMetadata(MediaMetadataRetriever.METADATA_KEY_VIDEO_WIDTH));
            int height = Integer.parseInt(retriever1.extractMetadata(MediaMetadataRetriever.METADATA_KEY_VIDEO_HEIGHT));
            retriever1.release();

            int videoDuration = Integer.parseInt(time);

            int newWidth = 1024;
            int newHeight = Math.round(height * (1024f / width));

            Bitmap bitmap;
            for(int i=0;i<videoDuration;i+=mFrameEvery){

                long startTime = System.currentTimeMillis();
                bitmap = retriever.getFrameAtTime(i*1000, FFmpegMediaMetadataRetriever.OPTION_CLOSEST);
                long endTime = System.currentTimeMillis();

                Log.d(TAG,"Took: " + ((endTime - startTime) / 1000f));

                final Bitmap scaledBitmap = Bitmap.createScaledBitmap(bitmap, newWidth, newHeight, false);

                try {
                    File frameFile = getOutputMediaFile("IMAGEFILE",rev.size());
                    FileOutputStream fos = new FileOutputStream(frameFile);
                    scaledBitmap.compress(Bitmap.CompressFormat.PNG, 80, fos);
                    fos.close();

                    rev.add(frameFile.getAbsolutePath());

                    runOnUiThread(new Runnable() {
                        @Override
                        public void run() {
                            imageView.setImageBitmap(scaledBitmap);
                            totalFrames.setText("Total Frames: " + rev.size());
                        }
                    });
                } catch (FileNotFoundException e) {
                    Log.d(TAG, "File not found: " + e.getMessage());
                } catch (IOException e) {
                    Log.d(TAG, "Error accessing file: " + e.getMessage());
                }
            }
            runOnUiThread(new Runnable() {
                @Override
                public void run() {
                    progressBar.setVisibility(View.INVISIBLE);
                    seekBar.setEnabled(true);
                }
            });
        }
    }).start();

日志:

D/EditVideo: Took: 1.448
D/EditVideo: Took: 1.147
D/EditVideo: Took: 1.162
D/EditVideo: Took: 1.322
D/EditVideo: Took: 1.301
D/EditVideo: Took: 1.453
D/EditVideo: Took: 1.108
D/EditVideo: Took: 1.165
D/EditVideo: Took: 1.292
D/EditVideo: Took: 1.358
D/EditVideo: Took: 1.369
D/EditVideo: Took: 1.06
D/EditVideo: Took: 1.13
D/EditVideo: Took: 1.183
D/EditVideo: Took: 1.177
D/EditVideo: Took: 1.231
D/EditVideo: Took: 0.924
D/EditVideo: Took: 1.007
D/EditVideo: Took: 1.092
D/EditVideo: Took: 1.104
D/EditVideo: Took: 1.211
D/EditVideo: Took: 0.923
D/EditVideo: Took: 0.994
D/EditVideo: Took: 1.119
D/EditVideo: Took: 1.138
D/EditVideo: Took: 1.193

Answer 1

我使用 MediaMetadataRetriver，平均处理时间约为 0.7 秒。我还找到了一些方法来减少获取框架的时间。