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• Inconsistent behaviour of ffmpeg -i flag

  19 mai 2021, par zeebrah

  I'm trying to write a Bash script that would download an audio track from youtube and convert it to Apple ringtone format, which is .m4r. The tools I employ are youtube-dl and ffmpeg. The former seems to work fine but I have a strange issue with the latter. When I try to pass the name of the file parametrically, shell prints that file or directory can't be found.

  


  I use the same method for unwraping user input (or my defaults) for both commands but it only seems to work with youtube-dl.

  


  Example of what doesn't work and print the text above. Obviously, all the files are in fact there and accessible

  


  youtube-dl -i --extract-audio --audio-format m4a -o $filepath_interim  --audio-quality 0 $video_link
ffmpeg -i $filepath_interim -acodec copy -f ipod -ss $offset  -t $length $filepath_out


  


  So, I tried to do it with '' strings, $(command) syntax, it all failed. I only found one way to make it work, which is to hard code the values of the paths but this defeats the whole purpose of my script.

  


  youtube-dl -i --extract-audio --audio-format m4a -o $filepath_interim  --audio-quality 0 $video_link
ffmpeg -i ~/Downloads/ringtone.m4a -acodec copy -f ipod -ss $offset  -t $length ~/Downloads/ringtone.m4r


  


  I want to figure out why this keeps happening, whether it is in any way specific to ffmpeg or am I just missing some piece of knowledge about $ name unwrapping.

  


  Minimal Working Example. Run with bash or pack in script and run. If your path to bash is different, please change the shebang :

  


  #!/usr/local/bin/bash
# initialise
filepath_interim="~/Downloads/ringtone.m4a"
filepath_out="~/Downloads/ringtone.m4r"
video_link="https://www.youtube.com/watch?v=dQw4w9WgXcQ"
offset=0
length=30

# main part
youtube-dl -i --extract-audio --audio-format m4a -o $filepath_interim  --audio-quality 0 $video_link
ffmpeg -i $filepath_interim -acodec copy -f ipod -ss $offset  -t $length $filepath_out


  


• How to minimize latency in ffmpeg stream Java ?

  13 juillet 2022, par Taavi Sõerd

  I need to stream ffmpeg video feed in android studio and need minimal latency. Code below has achieved that when playing on galaxy s21 ultra but when I play it on galaxy tab then it's like in slow motion. When i set buffer size to 0 I get minimal latency but can't actually even see the video as it's all corrupted (all gray and colored noise).

  


  public class Decode implements Runnable {
public Activity activity;
AVFrame pFrameRGB;
SwsContext sws_ctx;
ByteBuffer bitmapBuffer;
Bitmap bmp;
byte[] array;
int imageViewWidth = 0;
int imageViewHeight = 0;
boolean imageChanged = true;
int v_stream_idx = -1;
int klv_stream_idx = -1;

boolean imageDrawMutex = false;

boolean imageIsSet = false;
ImageView imageView =  MainActivity.getmInstanceActivity().findViewById(R.id.imageView);

String mFilename = "udp://@" + MainActivity.connectionIP;;
UasDatalinkLocalSet mLatestDls;

public Decode(Activity _activity) {
    this.activity = _activity;
}

public void create_decoder(AVCodecContext codec_ctx) {
    imageChanged = true;

    // Determine required buffer size and allocate buffer
    int numBytes =av_image_get_buffer_size(AV_PIX_FMT_RGBA, codec_ctx.width(),
            codec_ctx.height(), 1);
    BytePointer buffer = new BytePointer(av_malloc(numBytes));

    bmp = Bitmap.createBitmap(codec_ctx.width(), codec_ctx.height(), Bitmap.Config.ARGB_8888);

    array = new byte[codec_ctx.width() * codec_ctx.height() * 4];
    bitmapBuffer = ByteBuffer.wrap(array);

    sws_ctx = sws_getContext(
            codec_ctx.width(),
            codec_ctx.height(),
            codec_ctx.pix_fmt(),
            codec_ctx.width(),
            codec_ctx.height(),
            AV_PIX_FMT_RGBA,
            SWS_POINT,
            null,
            null,
            (DoublePointer) null
    );

    if (sws_ctx == null) {
        Log.d("app", "Can not use sws");
        throw new IllegalStateException();
    }

    av_image_fill_arrays(pFrameRGB.data(), pFrameRGB.linesize(),
            buffer, AV_PIX_FMT_RGBA, codec_ctx.width(), codec_ctx.height(), 1);
}

@Override
public void run() {
    Log.d("app", "Start decoder");

    int ret = -1, i = 0;
    String vf_path = mFilename;

    AVFormatContext fmt_ctx = new AVFormatContext(null);
    AVPacket pkt = new AVPacket();


    AVDictionary multicastDict = new AVDictionary();

    av_dict_set(multicastDict, "rtsp_transport", "udp_multicast", 0);

    av_dict_set(multicastDict, "localaddr", getIPAddress(true), 0);
    av_dict_set(multicastDict, "reuse", "1", 0);

    av_dict_set(multicastDict, "buffer_size", "0.115M", 0);

    ret = avformat_open_input(fmt_ctx, vf_path, null, multicastDict);
    if (ret < 0) {
        Log.d("app", String.format("Open video file %s failed \n", vf_path));
        byte[] error_message = new byte[1024];
        int elen = av_strerror(ret, error_message, 1024);
        String s = new String(error_message, 0, 20);
        Log.d("app", String.format("Return: %d", ret));
        Log.d("app", String.format("Message: %s", s));
        throw new IllegalStateException();
    }
    
    if (avformat_find_stream_info(fmt_ctx, (PointerPointer) null) < 0) {
        //System.exit(-1);
        Log.d("app", "Stream info not found");
    }


    avformat.av_dump_format(fmt_ctx, 0, mFilename, 0);

    int nstreams = fmt_ctx.nb_streams();

    for (i = 0; i < fmt_ctx.nb_streams(); i++) {
        if (fmt_ctx.streams(i).codecpar().codec_type() == AVMEDIA_TYPE_VIDEO) {
            v_stream_idx = i;
        }
        if (fmt_ctx.streams(i).codecpar().codec_type() == AVMEDIA_TYPE_DATA) {
            klv_stream_idx = i;
        }
    }
    if (v_stream_idx == -1) {
        Log.d("app", "Cannot find video stream");
        throw new IllegalStateException();
    } else {
        Log.d("app", String.format("Video stream %d with resolution %dx%d\n", v_stream_idx,
                fmt_ctx.streams(v_stream_idx).codecpar().width(),
                fmt_ctx.streams(v_stream_idx).codecpar().height()));
    }

    AVCodecContext codec_ctx = avcodec_alloc_context3(null);
    avcodec_parameters_to_context(codec_ctx, fmt_ctx.streams(v_stream_idx).codecpar());


    AVCodec codec = avcodec_find_decoder(codec_ctx.codec_id());


    AVDictionary avDictionary = new AVDictionary();

    av_dict_set(avDictionary, "fflags", "nobuffer", 0);


    if (codec == null) {
        Log.d("app", "Unsupported codec for video file");
        throw new IllegalStateException();
    }
    ret = avcodec_open2(codec_ctx, codec, avDictionary);
    if (ret < 0) {
        Log.d("app", "Can not open codec");
        throw new IllegalStateException();
    }

    AVFrame frm = av_frame_alloc();

    // Allocate an AVFrame structure
    pFrameRGB = av_frame_alloc();
    if (pFrameRGB == null) {
        //System.exit(-1);
        Log.d("app", "unable to init pframergb");
    }

    create_decoder(codec_ctx);

    int width = codec_ctx.width();
    int height = codec_ctx.height();

    double fps = 15;
    

    while (true) {
        try {
            Thread.sleep(1);
        } catch (Exception e) {

        }

        try {
            if (av_read_frame(fmt_ctx, pkt) >= 0) {
                if (pkt.stream_index() == v_stream_idx) {
                    avcodec_send_packet(codec_ctx, pkt);

                    if (codec_ctx.width() != width || codec_ctx.height() != height) {
                        create_decoder(codec_ctx);
                        width = codec_ctx.width();
                        height = codec_ctx.height();
                    }
                }

                if (pkt.stream_index() == klv_stream_idx) {

                    byte[] klvDataBuffer = new byte[pkt.size()];

                    for (int j = 0; j < pkt.size(); j++) {
                        klvDataBuffer[j] = pkt.data().get(j);
                    }

                    try {
                        KLV k = new KLV(klvDataBuffer, KLV.KeyLength.SixteenBytes, KLV.LengthEncoding.BER);
                        byte[] main_payload = k.getValue();

                        // decode the Uas Datalink Local Set from main_payload binary blob.
                        mLatestDls = new UasDatalinkLocalSet(main_payload);

                        if (mLatestDls != null) {

                            MainActivity.getmInstanceActivity().runOnUiThread(new Runnable() {
                                @RequiresApi(api = Build.VERSION_CODES.Q)
                                @Override
                                public void run() {
                                    MainActivity.getmInstanceActivity().updateKlv(mLatestDls);
                                }
                            });
                        }
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                    
                }

                int wasFrameDecoded = 0;
                while (wasFrameDecoded >= 0) {
                    wasFrameDecoded = avcodec_receive_frame(codec_ctx, frm);

                    if (wasFrameDecoded >= 0) {
                        // get clip fps
                        fps = 15; //av_q2d(fmt_ctx.streams(v_stream_idx).r_frame_rate());

                        sws_scale(
                                sws_ctx,
                                frm.data(),
                                frm.linesize(),
                                0,
                                codec_ctx.height(),
                                pFrameRGB.data(),
                                pFrameRGB.linesize()
                        );

                        if(!imageDrawMutex) {
                            MainActivity.getmInstanceActivity().runOnUiThread(new Runnable() {
                                @Override
                                public void run() {
                                    if (imageIsSet) {
                                        imageDrawMutex = true;
                                        pFrameRGB.data(0).position(0).get(array);
                                        bitmapBuffer.rewind();
                                        bmp.copyPixelsFromBuffer(bitmapBuffer);

                                        if (imageChanged) {
                                            (imageView).setImageBitmap(bmp);
                                            imageChanged = false;
                                        }

                                        (imageView).invalidate();
                                        imageDrawMutex = false;
                                    } else {
                                        (imageView).setImageBitmap(bmp);
                                        imageIsSet = true;
                                    }
                                }
                            });
                        }
                    }
                }
                av_packet_unref(pkt);

            }
        } catch (Exception e) {
            e.printStackTrace();
        }

        if (false) {
            Log.d("threads", "false");

            av_frame_free(frm);

            avcodec_close(codec_ctx);
            avcodec_free_context(codec_ctx);

            avformat_close_input(fmt_ctx);
        }
    }
}


  


  This code is running in Android Studio with Java. I'm quite new on this topic so not really sure even where to start.
What could be the cause of that ?

  


• avformat/mpegts : parse sections with multiple tables

  9 mai 2018, par Aman Gupta

  avformat/mpegts : parse sections with multiple tables
  Fixes PMT parsing in some mpegts streams which contain
  
  multiple tables within the PMT pid. Previously, the parser
  
  assumed only one table was present in each packet, and discarded
  
  the rest of the section data after attempting to parse the first
  
  table.
  A similar issue was documented in the BeyondTV software[1], which
  
  helped me diagnose the same bug in the ffmpeg mpegts demuxer. I also
  
  tried DVBInspector, libdvbpsi's dvbinfo, and tstools' tsinfo to
  
  help debug. The former two properly read PMTs with multiple tables,
  
  whereas the last has the same bug as ffmpeg.
  I've created a minimal sample[2] which contains the combined PMT.
  
  Here's what ffmpeg probe shows before and after this patch :
  Before :
      Input #0, mpegts, from 'combined-pmt-tids.ts' :
  
        Duration : 00:00:01.08, start : 4932.966167, bitrate : 741 kb/s
  
        Program 1
  
        No Program
  
          Stream #0:0[0xf9d] : Audio : ac3, 48000 Hz, mono, fltp, 96 kb/s
  
          Stream #0:1[0xf9b] : Audio : mp3, 0 channels, fltp
  
          Stream #0:2[0xf9c] : Unknown : none
  After :
      Input #0, mpegts, from 'combined-pmt-tids.ts' :
  
        Duration : 00:00:01.11, start : 4932.966167, bitrate : 718 kb/s
  
        Program 1
  
          Stream #0:0[0xf9b] : Video : mpeg2video ([2][0][0][0] / 0x0002), none(tv, top first), 29.97 fps, 29.97 tbr, 90k tbn, 90k tbc
  
          Stream #0:1[0xf9c](eng) : Audio : ac3 (AC-3 / 0x332D4341), 48000 Hz, 5.1(side), fltp, 384 kb/s
  
          Stream #0:2[0xf9d](spa) : Audio : ac3 (AC-3 / 0x332D4341), 48000 Hz, mono, fltp, 96 kb/s
  With the patch, the PMT is parsed correctly so the streams are
  
  created in the correct order, are associated with "Program 1",
  
  and their codecs are set correctly.
  [1] http://forums.snapstream.com/vb/showpost.php?p=343816&postcount=201
  
  [2] https://s3.amazonaws.com/tmm1/combined-pmt-tids.ts
  Signed-off-by : Aman Gupta <aman@tmm1.net>
  
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavformat/mpegts.c