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• Convert audio to MP3 : 4 frames left in the queue on closing

  21 août 2024, par Vololodymyr

  I am trying to convert AMR audio to MP3 :

  


          ByteArrayInputStream amrStream = new ByteArrayInputStream(amrData);
        ByteArrayOutputStream mp3Stream = new ByteArrayOutputStream();

        try (FFmpegFrameGrabber grabber = new FFmpegFrameGrabber(amrStream);
             FFmpegFrameRecorder recorder = new FFmpegFrameRecorder(mp3Stream, grabber.getAudioChannels())) {
            
            grabber.setFormat("amr");
            grabber.start();

            recorder.setFormat("mp3");
            int sampleRate = grabber.getSampleRate();

            recorder.setSampleRate( sampleRate < MIN_SAMPLE_RATE ? MIN_SAMPLE_RATE : sampleRate);
            recorder.setAudioChannels(grabber.getAudioChannels());

            // The AMR low bitrate sounds better then same bitrate on mp3, so we increase it
            int bitrate = grabber.getAudioBitrate();
            recorder.setAudioBitrate(bitrate < MIN_BITRATE ? MIN_BITRATE : bitrate);
            recorder.start();

            Frame frame;
            while ((frame = grabber.grab()) != null) {
                if (frame.samples != null) {
                    recorder.record(frame);
                }
            }
            recorder.flush();
            recorder.release();
            grabber.release();
            recorder.stop();
            grabber.stop();
        } catch (Exception e) {
            throw new IOException("Failed to convert AMR to MP3", e);
        }


  


  For some reason, the output mp3 file is always cut for half of a second.

  


  And in logs, I can see :
[libmp3lame @ 000002106e0b26c0] 4 frames left in the queue on closing

  


  Any ideas on how I can flush those 4 frames to my output steam ?
I tried flushing with Thread.sleep(), other order of release/stop calls, nothing works.

  


• FFMpeg jni in Android ?

  4 février 2014, par Whyhow

  I have built FFMPEG executables and libraries as provided by Bambuser (http://bambuser.com/opensource). So I managed to build the Android executables and libraties. How can I link these libs in my Eclipse project and invoke the FFmpeg functions from Java ? The open source code includes the C header-files.

  I am new to native coding for Android, and I could not find an easy answer for this. In basic : having a bunch of Android compatible libraries and some C header files what do I have to do to reuse those libaries' functionality from java (+Android SDK) ?

  Any help would be appreciated.

  Kind regards,

  WhyHow

• Feeding raw image bytes into ffmpeg rawvideo fails with Invalid buffer size on linux only

  13 février 2021, par cherouvim

  I have a nodejs program which generates raw (rgb24) image(s), which I then pipe into ffmpeg so it saves as png or mp4. My code looks like this :

  


  const fs = require("fs");
// ...
const outputBuffer = Buffer.alloc(outputPngWidth * 3 * outputPngHeight);
// ... write data into outputBuffer
fs.writeSync(process.stdout.fd, outputBuffer);


  


  I then do the following in CLI :

  


  node generate | ffmpeg -f rawvideo -pixel_format rgb24 -video_size 1000x1000 -i - test.png


  


  Alternatively, if I generate lots of images from my program, I do this to generate the video file :

  


  node generate | ffmpeg -f rawvideo -pixel_format rgb24 -video_size 1000x1000 -r 60 -i - -codec:v libx265 test.mp4


  


  On windows this works flawlessly. On linux (either on Ubuntu 20 VM, or Ubuntu 20 installed directly on a physical machine), it consistently fails with :

  


  pipe:: corrupt input packet in stream 0
[rawvideo @ 0x55f5256c8040] Invalid buffer size, packet size 65536 < expected frame_size 3000000
Error while decoding stream #0:0: Invalid argument


  


  If I split this in 2 phases like so, then it works perfectly on linux as well :

  


  node generate > test.raw
cat test.raw | ffmpeg -f rawvideo -pixel_format rgb24 -video_size 1000x1000 -i - test.png


  


  By looking at the error "packet size 65536 < expected frame_size 3000000" it seems that node's fs.writeSync only sends 65536 bytes at a time, but ffmpeg expects 3000000 bytes (that is 1000 width * 1000 height * 3 channels).

  &#xA;

  If I reduce my image size to something small, e.g 50x50 or 100x100, then it works. As soon as x * y * 3 exceeds 65536, it fails (eg. 160x160 fails with "packet size 65536 < expected frame_size 76800" because 160 * 160 * 3 = 76800).

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  What I've tried so far to solve the issue without luck :

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  • Force node to spit out the whole buffer at once :

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  fs.writeSync(process.stdout.fd, outputBuffer, 0, outputBuffer.length);


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  • All suggestions of Add a big buffer to a pipe between two commands with various linux commands to buffer between node and ffmpeg.

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  • Use Ubuntu 18 instead of 20.

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  • Use node 12 instead of 15.

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  • Figure out a way to change the chunk size in https://nodejs.org/api/fs.html

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  Is there a way to overcome this ?

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