Recherche avancée

Sur d’autres sites (5745)

• ffmpeg How to SCROLL (draw text) on an overlayed image not on the main video

  17 juillet 2020, par Tony Hanna

  i want to draw a scrolling text with left and right margin over an OVERLAYED image .. like let's say a BREAKING NEWS Header and then below it the scrolling text.. but i dont want the scrolling to start at the point 0 .. i wanted to be bound by the image overlay position and margins .. i tried this code :

  


  ffmpeg -re -i lethal.mkv -i template.png -filter_complex "[1:v]drawtext =fontsize=24:fontcolor=white:fontfile='arial.ttf':textfile='test.txt':x=w-mod(max(t-1\,0)*(80)\, 2*(tw+100)):y=10[1v];[0:v][1v]overlay=30:30[over]" -map [over] -c:a copy -c:v libx264 -f mpegts udp://224.2.2.1:1234

  


  when i do that .. the text doesn't show .. or i'm guessing it's showing behind the image .. i don't know ! Any help please

  


• use ffmpeg in vba to change video format

  3 juillet 2020, par Iban Arriola

  I want to change the video format of the embedded videos that appears in a presentation. I achieve to export the video file to another folder using the following code :

  



          Dim Finame As Variant
        Dim oApp As Object
        Dim StoreFolder As Variant
        Dim Videoname As Variant
        Dim FileNameFolder As Variant

        MkDir "C:\template\videoZip"

        Set oApp = CreateObject("Shell.Application")
        FileNameFolder = "C:\template\videoZip\"
        Finame = ActivePresentation.Path & "\" & ActivePresentation.Name
        StoreFolder = "C:\template\created_files\"
        oApp.Namespace("C:\template\videoZip\").CopyHere Finame
        Name "C:\template\videoZip\" & ActivePresentation.Name As "C:\template\videoZip\" & ActivePresentation.Name & ".zip"


        oApp.Namespace(FileNameFolder).CopyHere oApp.Namespace("C:\template\videoZip\" & ActivePresentation.Name & ".zip").items

        Dim firstCount As Integer
        Dim lastCount As Integer

        For j = 1 To videoNum
            firstCount = oApp.Namespace(StoreFolder).items.count
            Videoname = "C:\template\videoZip\ppt\media\media" & j & ".mp4"
            oApp.Namespace(StoreFolder).CopyHere Videoname
            lastCount = oApp.Namespace(StoreFolder).items.count
            If firstCount = lastCount Then
                MsgBox "The video has problems loading and it will not be shown (Only mp4 supported)"
            End If
        Next j

        Set objFSO = CreateObject("Scripting.FileSystemObject")
        objFSO.deletefolder "C:\template\videoZip"
    End If


  



  As I said, with this peace of code I can get all the videos that are in the presentation. Now I want to change the format of them. I heard that it is possible using ffmpeg. Other solutions to change format are welcome too.

  


• MediaCodec AV Sync when decoding

  12 juin 2020, par ClassA

  All of the questions regarding syncing audio and video, when decoding using MediaCodec, suggests that we should use an "AV Sync" mechanism to sync the video and audio using their timestamps.

  



  Here is what I do to achieve this :

  



  I have 2 threads, one for decoding video and one for audio. To sync the video and audio I'm using Extractor.getSampleTime() to determine if I should release the audio or video buffers, please see below :

  



  //This is called after configuring MediaCodec(both audio and video)
private void startPlaybackThreads(){
    //Audio playback thread
    mAudioWorkerThread = new Thread("AudioThread") {
        @Override
        public void run() {
            if (!Thread.interrupted()) {
                try {
                    //Check info below
                    if (shouldPushAudio()) {
                        workLoopAudio();
                    }
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }
    };
    mAudioWorkerThread.start();

    //Video playback thread
    mVideoWorkerThread = new Thread("VideoThread") {
        @Override
        public void run() {
            if (!Thread.interrupted()) {
                try {
                    //Check info below
                    if (shouldPushVideo()) {
                        workLoopVideo();
                    }
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }
    };
    mVideoWorkerThread.start();
}

//Check if more buffers should be sent to the audio decoder
private boolean shouldPushAudio(){
    int audioTime =(int) mAudioExtractor.getSampleTime();
    int videoTime = (int) mExtractor.getSampleTime();
    return audioTime <= videoTime;
}
//Check if more buffers should be sent to the video decoder
private boolean shouldPushVideo(){
    int audioTime =(int) mAudioExtractor.getSampleTime();
    int videoTime = (int) mExtractor.getSampleTime();
    return audioTime > videoTime;
}


  



  Inside workLoopAudio() and workLoopVideo() is all my MediaCodec logic (I decided not to post it because it's not relevant).

  



  So what I do is, I get the sample time of the video and the audio tracks, I then check which one is bigger(further ahead). If the video is "ahead" then I pass more buffers to my audio decoder and visa versa.

  



  This seems to be working fine - The video and audio are playing in sync.

  



  ---

  



  My question :

  



  I would like to know if my approach is correct(is this how we should be doing it, or is there another/better way) ? I could not find any working examples of this(written in java/kotlin), thus the question.

  



  ---

  



  EDIT 1 :

  



  I've found that the audio trails behind the video (very slightly) when I decode/play a video that was encoded using FFmpeg. If I use a video that was not encoded using FFmpeg then the video and audio syncs perfectly.

  



  The FFmpeg command is nothing out of the ordinary :

  



  -i inputPath -crf 18 -c:v libx264 -preset ultrafast OutputPath


  



  I will be providing additional information below :

  



  I initialize/create AudioTrack like this :

  



  //Audio
mAudioExtractor = new MediaExtractor();
mAudioExtractor.setDataSource(mSource);
int audioTrackIndex = selectAudioTrack(mAudioExtractor);
if (audioTrackIndex < 0){
    throw new IOException("Can't find Audio info!");
}
mAudioExtractor.selectTrack(audioTrackIndex);
mAudioFormat = mAudioExtractor.getTrackFormat(audioTrackIndex);
mAudioMime = mAudioFormat.getString(MediaFormat.KEY_MIME);

mAudioChannels = mAudioFormat.getInteger(MediaFormat.KEY_CHANNEL_COUNT);
mAudioSampleRate = mAudioFormat.getInteger(MediaFormat.KEY_SAMPLE_RATE);

final int min_buf_size = AudioTrack.getMinBufferSize(mAudioSampleRate, (mAudioChannels == 1 ? AudioFormat.CHANNEL_OUT_MONO : AudioFormat.CHANNEL_OUT_STEREO), AudioFormat.ENCODING_PCM_16BIT);
final int max_input_size = mAudioFormat.getInteger(MediaFormat.KEY_MAX_INPUT_SIZE);
mAudioInputBufSize =  min_buf_size > 0 ? min_buf_size * 4 : max_input_size;
if (mAudioInputBufSize > max_input_size) mAudioInputBufSize = max_input_size;
final int frameSizeInBytes = mAudioChannels * 2;
mAudioInputBufSize = (mAudioInputBufSize / frameSizeInBytes) * frameSizeInBytes;

mAudioTrack = new AudioTrack(AudioManager.STREAM_MUSIC,
    mAudioSampleRate,
    (mAudioChannels == 1 ? AudioFormat.CHANNEL_OUT_MONO : AudioFormat.CHANNEL_OUT_STEREO),
    AudioFormat.ENCODING_PCM_16BIT,
    AudioTrack.getMinBufferSize(mAudioSampleRate, mAudioChannels == 1 ? AudioFormat.CHANNEL_OUT_MONO : AudioFormat.CHANNEL_OUT_STEREO, AudioFormat.ENCODING_PCM_16BIT),
    AudioTrack.MODE_STREAM);

try {
    mAudioTrack.play();
} catch (final Exception e) {
    Log.e(TAG, "failed to start audio track playing", e);
    mAudioTrack.release();
    mAudioTrack = null;
}


  



  And I write to the AudioTrack like this :

  



  //Called from within workLoopAudio, when releasing audio buffers
if (bufferAudioIndex >= 0) {
    if (mAudioBufferInfo.size > 0) {
        internalWriteAudio(mAudioOutputBuffers[bufferAudioIndex], mAudioBufferInfo.size);
    }
    mAudioDecoder.releaseOutputBuffer(bufferAudioIndex, false);
}

private boolean internalWriteAudio(final ByteBuffer buffer, final int size) {
    if (mAudioOutTempBuf.length < size) {
        mAudioOutTempBuf = new byte[size];
    }
    buffer.position(0);
    buffer.get(mAudioOutTempBuf, 0, size);
    buffer.clear();
    if (mAudioTrack != null)
        mAudioTrack.write(mAudioOutTempBuf, 0, size);
    return true;
}


  



  "NEW" Question :

  



  The audio trails about 200ms behind the video if I use a video that was encoded using FFmpeg, is there a reason why this could be happening ?