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• Inconsistant rendering in mlt XML and C interface and 'hold' producer and avformat consumer

  14 octobre 2016, par Leif Andersen

  I am trying to create a short video that is just a single image. (I know its a bit silly, but its a test for something bigger).

  The code I have for rendering it is :

  #include <framework></framework>mlt.h>
  
  #include 
  
  #include 
  
  
  
  int main() {
  
    if(mlt_factory_init(NULL)) {
  
      mlt_profile p = mlt_profile_init(NULL);
  
      mlt_consumer target = mlt_factory_consumer(p, "avformat", 
  
      mlt_producer source = mlt_factory_producer(p, "hold", "/Users/leif/logo.png");
  
      mlt_producer_set_in_and_out(source, 0, 10);
  
      mlt_consumer_connect(target, mlt_producer_service(source));
  
      mlt_consumer_start(target);
  
  
  
      sleep(5);
  
      mlt_consumer_stop(target);
  
  
  
      mlt_consumer_close(target);
  
      mlt_producer_close(source);
  
      mlt_factory_close();
  
    } else {
  
      printf("No\n");
  
    }
  
  
  
    return 0;
  
  }

  Where logo.png is this file.

  When I run this code and play output.mp4, the picture comes out all garbelled. There is a green line in the middle and the logo is superimposed on itself a lot.

  On the other hand, if I change the consumer to be SDL, the image plays just fine.

  And finally, if I change the consumer to be XML, and then use the melt command line application to render it :

  melt -consumer avformat:xmlout.mp4 output.xml

  and play the video, it also plays fine.

  Is there something I am missing in the avformat consumer that I should be setting ? Or something else that I am missing here ?

  Edit : For reference, the outputted xml file : output.xml is :

  <?xml version="1.0" encoding="utf-8"?>
  
  <mlt version="6.2.0" root="/Users/leif/src/video/private" title="Anonymous Submission" parent="producer0" in="0" out="10">
  
        <profile description="DV/DVD PAL" width="720" height="576" progressive="0" colorspace="601"></profile>
  
    <producer title="Anonymous Submission" in="0" out="10">
  
      <property>15000</property>
  
      <property>pause</property>
  
      <property>/Users/leif/logo.png</property>
  
      <property>1.06667</property>
  
      <property>0</property>
  
      <property>onefield</property>
  
      <property>hold</property>
  
      <property>1</property>
  
    </producer>
  
  </mlt>

• lavc/bswapdsp : RISC-V B bswap_buf

  2 octobre 2022, par Rémi Denis-Courmont

  lavc/bswapdsp : RISC-V B bswap_buf
  Simply taking the Zbb REV8 instruction into use in a simple loop gives
  
  some significant savings :
  bswap_buf_c : 1081.0
  
  bswap_buf_rvb_b : 771.0
  But we can also use the 64-bit REV8 as a pseudo-SIMD instruction with
  
  just one additional shift, and one fewer load, effectively doubling the
  
  bandwidth. Consequently, this patch is useful even if the compile-time
  
  target has Zbb enabled for C code :
  bswap_buf_c : 1081.0
  
  bswap_buf_rvb_b : 341.0  (this patch)
  On the other hand, this approach fails miserably for bswap16_buf as the
  
  ratio of shifts and stores becomes unfavorable compared to naïve C :
  bswap16_buf_c : 1542.0
  
  bswap16_buf_rvb_b : 1803.7
  Unrolling to process 128 bits (4 samples) at a time actually worsens
  
  performance ever so slightly :
  bswap_buf_c : 1081.0
  
  bswap_buf_rvb_b : 408.5
  

  • [DH] libavcodec/bswapdsp.c
  • [DH] libavcodec/bswapdsp.h
  • [DH] libavcodec/riscv/Makefile
  • [DH] libavcodec/riscv/bswapdsp_init.c
  • [DH] libavcodec/riscv/bswapdsp_rvb.S

• WebP encoder : use WebPAnimEncoder API when available.

  20 mai 2015, par Urvang Joshi

  WebP encoder : use WebPAnimEncoder API when available.
  WebPAnimEncoder API is a combination of encoder (WebPEncoder) and muxer
  
  (WebPMux). It performs several optimizations to make it more efficient
  
  than the combination of WebPEncode() and native ffmpeg muxer.
  When WebPAnimEncoder API is used :
  
   In the encoder layer : we use WebPAnimEncoderAdd() instead of
  
    WebPEncode().
  
   The muxer layer : works like a raw muxer.
  On the other hand, when WebPAnimEncoder API isn’t available, the old code is
  
  used as it is :
  
   In the codec layer : WebPEncode is used to encode each frame
  
   In the muxer layer :  ffmpeg muxer is used
  Signed-off-by : Michael Niedermayer <michaelni@gmx.at>
  

  • [DH] Changelog
  • [DH] configure
  • [DH] libavcodec/Makefile
  • [DH] libavcodec/allcodecs.c
  • [DH] libavcodec/libwebpenc_animencoder.c
  • [DH] libavcodec/version.h