Android Mediarecorder: Getting 3GP instead of MPEG4

问题

I want to record video only in android with MPEG4 format. I want the container and codec to be MPEG4. So here is what I have done for that.

Thread video = new Thread(new Runnable() {
    public void run() {
        videoRecorder = new MediaRecorder();
        videoRecorder.setPreviewDisplay(surfaceView.getHolder().getSurface());
        videoRecorder.setVideoSource(MediaRecorder.VideoSource.DEFAULT);
        videoRecorder.setOutputFormat(MediaRecorder.OutputFormat.MPEG_4);
        videoRecorder.setVideoEncodingBitRate(56 * 8 * 1024);
        videoRecorder.setVideoSize(176, 144);
        videoRecorder.setVideoFrameRate(12);
        videoRecorder.setVideoEncoder(MediaRecorder.VideoEncoder.MPEG_4_SP);
        videoRecorder.setOutputFile("/sdcard/video.m4e");
        try {
            videoRecorder.prepare();
        } catch (IllegalStateException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        videoRecorder.start();
    }
});
video.start();

Now, after recording, I got the video recorded into video.m4e file. But when I check its information, I got the following:

At the same time I used the following to record audio:

Thread audio = new Thread(new Runnable() {              
    public void run() {
        audioRecorder = new MediaRecorder();
        audioRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);
        audioRecorder.setOutputFormat(MediaRecorder.OutputFormat.RAW_AMR);
        audioRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);
        audioRecorder.setOutputFile("/sdcard/audio.amr");
        try {
            audioRecorder.prepare();
        } catch (IllegalStateException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        audioRecorder.start();
    }
});
audio.start();

and I got the container format and codec as AMR as I intended:

So, what causes MediaRecorder to record video in 3GP format? I haven't specified 3GP anywhere in my program. I am testing this code on my Samsung Galaxy tab running Android 2.2

回答1:

MPEG-4 is a method of defining compression of audio and visual (AV) digital data.

A file format for storing time-based media content. It is a general format forming the basis for a number of other more specific file formats (e.g. 3GP, Motion JPEG 2000, MPEG-4 Part 14).

So there is no conspiracy in the result you got, the compression method (OR "Codec") you used was MPEG4 and the video format generated by your phone is 3gp, which in actual is a part of the video formats of the suite of the MPEG4 compression scheme for the media.

回答2:

This is defined by the frameworks. Specifically it has a set of parameters that are found in the MediaRecorder class that define what all is supported.

回答3:

I do not understand akkilis's explanation.

In the official Android tutorial "MediaRecorder.OutputFormat", MPEG_4 is one of options of "media file formats", parallel to THREE_GPP. int AAC_ADTS AAC ADTS file format int AMR_NB AMR NB file format int AMR_WB AMR WB file format int DEFAULT
int MPEG_4 MPEG4 media file format int RAW_AMR This constant was deprecated in API level 16. Deprecated in favor of MediaRecorder.OutputFormat.AMR_NB int THREE_GPP 3GPP media file format

There is another parameter to specify the encoding format: "MediaRecorder.VideoEncoder"

int DEFAULT
int H263
int H264
int MPEG_4_SP

In OP's code, he specified both file format and encoding format.