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• avformat/mov : Add option to ignore chapters during parsing

  10 novembre 2015, par Bryan Huh

  avformat/mov : Add option to ignore chapters during parsing
  Chapter-indexing can be expensive since chapters may be interspersed
  
  throughout the entire file and may require many seeks - especially
  
  costly when consuming a video over a remote protocol like http.
  
  Furthermore it is often unnecessary, especially when only trying to get
  
  video info (e.g. via ffprobe).
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavformat/isom.h
  • [DH] libavformat/mov.c

• JavaCV : avformat_open_input() hangs (not network, but with custom AVIOContext)

  14 octobre 2015, par Yun Tao Hai

  I’m using a custom AVIOContext to bridge FFMpeg with java IO. The function avformat_open_input() never returns. I have searched the web for similar problems, all of which were caused by faulty network or wrong server configurations. However, I’m not using network at all, as you can see in the following little program :

  package com.example;
  
  
  
  import org.bytedeco.javacpp.*;
  
  import java.io.File;
  
  import java.io.IOException;
  
  import java.io.RandomAccessFile;
  
  import static org.bytedeco.javacpp.avcodec.*;
  
  import static org.bytedeco.javacpp.avformat.*;
  
  import static org.bytedeco.javacpp.avutil.*;
  
  import static org.bytedeco.javacpp.avdevice.*;
  
  import static org.bytedeco.javacpp.avformat.AVFormatContext.*;
  
  
  
  public class Test {
  
  
  
      public static void main(String[] args) throws Exception {
  
          File dir = new File(System.getProperty("user.home"), "Desktop");
  
          File file = new File(dir, "sample.3gp");
  
          final RandomAccessFile raf = new RandomAccessFile(file, "r");
  
  
  
          Loader.load(avcodec.class);
  
          Loader.load(avformat.class);
  
          Loader.load(avutil.class);
  
          Loader.load(avdevice.class);
  
          Loader.load(swscale.class);
  
          Loader.load(swresample.class);
  
  
  
          avcodec_register_all();
  
          av_register_all();
  
          avformat_network_init();
  
          avdevice_register_all();
  
  
  
          Read_packet_Pointer_BytePointer_int reader = new Read_packet_Pointer_BytePointer_int() {
  
              @Override
  
              public int call(Pointer pointer, BytePointer buf, int bufSize) {
  
                  try {
  
                      byte[] data = new byte[bufSize]; // this is inefficient, just use as a quick example
  
                      int read = raf.read(data);
  
  
  
                      if (read <= 0) {
  
                          System.out.println("EOF found.");
  
                          return AVERROR_EOF;
  
                      }
  
  
  
                      System.out.println("Successfully read " + read + " bytes of data.");
  
                      buf.position(0);
  
                      buf.put(data, 0, read);
  
                      return read;
  
                  } catch (Exception ex) {
  
                      ex.printStackTrace();
  
                      return -1;
  
                  }
  
              }
  
          };
  
  
  
          Seek_Pointer_long_int seeker = new Seek_Pointer_long_int() {
  
              @Override
  
              public long call(Pointer pointer, long offset, int whence) {
  
                  try {
  
                      raf.seek(offset);
  
                      System.out.println("Successfully seeked to position " + offset + ".");
  
                      return offset;
  
                  } catch (IOException ex) {
  
                      return -1;
  
                  }
  
              }
  
          };
  
  
  
          int inputBufferSize = 32768;
  
          BytePointer inputBuffer = new BytePointer(av_malloc(inputBufferSize));
  
          AVIOContext ioContext = avio_alloc_context(inputBuffer, inputBufferSize, 1, null, reader, null, seeker);
  
          AVInputFormat format = av_find_input_format("3gp");
  
          AVFormatContext formatContext = avformat_alloc_context();
  
          formatContext.iformat(format);
  
          formatContext.flags(formatContext.flags() | AVFMT_FLAG_CUSTOM_IO);
  
          formatContext.pb(ioContext);
  
  
  
          // This never returns. And I can never get result.
  
          int result = avformat_open_input(formatContext, "", format, null);
  
  
  
          // all clean-up code omitted for simplicity
  
      }
  
  
  
  }

  And below is my sample console output :

  Successfully read 32768 bytes of data.
  
  Successfully read 32768 bytes of data.
  
  Successfully read 32768 bytes of data.
  
  Successfully read 32768 bytes of data.
  
  Successfully read 32768 bytes of data.
  
  Successfully read 7240 bytes of data.
  
  EOF found.

  I’ve checked the sum of bytes, which corresponds to the file size ; EOF is also hit, meaning the file is completely read. Actually I am a bit skeptical as why avformat_open_input() would even read the entire file and still without returning ? There must be something wrong with what I am doing. Can any expert shed some lights or point me to the right direction ? I’m new to javacv and ffmpeg and especially to programming with Buffers and stuff. Any help, suggestion or criticism is welcome. Thanks in advance.

• python imageIO() ffmpeg output 3D ndarray

  27 juillet 2017, par Daimoj

  I’m trying to encode and than decode a collection of images using imageIO in python with the ffmpeg plugin and the HEVC codec.

  The stream I’m using is an ndarray of shape (1024,512). When I use the writer.append_data() on each image, the shape is as above (1024,512). After writer.close() is called, I create another reader on the video just made from above. When interrogating a single image of the video it’s shape is (1024,512,3). This is all grayscale, so I only expected an array of uint8’s in the shape of (1024,512). Why did ImageIO add 2 more dimensions to my video ? I only want one.