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• avcodec/ffv1_parser : Rename close to ffv1_close

  19 février, par Zhao Zhili

  avcodec/ffv1_parser : Rename close to ffv1_close
  This fixed wasm checkasm failure
  $ wasm-tools validate tests/checkasm/checkasm
  
  error : wasisdk ://v25.0/build/sysroot/wasi-libc-wasm32-wasip1-threads/libc-top-half/musl/src/stdio/__stdio_close.c:24:9 function `__stdio_close` failed to validate
  Caused by :
  
      0 : func 4581 failed to validate
  
      1 : type mismatch : expected i32 but nothing on stack (at offset 0x43b770)
  Since close is declared as static function, it's more like a bug
  
  in wasi sdk, but we can workaround it easily.
  Signed-off-by : Zhao Zhili <zhilizhao@tencent.com>
  
  Reviewed-by : James Almer <jamrial@gmail.com>
  

  • [DH] libavcodec/ffv1_parser.c

• How can I stream raw video frames AND audio to FFMPEG with Python 2.7 ?

  18 novembre 2017, par Just Askin

  I am streaming raw video frames from Pygame to FFMPEG, then sending to a rtmp stream, but for the life of me, I can’t figure out how to send live audio using the same Python module. It does not need to be the Pygame mixer, but I am not opposed to using it if that is where the best answer lies. I’m pretty sure it’s not though.

  My question is this : What is the best strategy to send live audio output from a program to FFMPEG along with raw video frames simultaneously from the same Python module ?

  My program is large, and eventually I would like to build options to switch audio inputs from a queue of music, a microphone, or any other random sounds from any program I want to use. But for the time being, I just want something to work. I am starting off with a simple Espeak command.

  Here is my Python commands :

  command = ['ffmpeg', '-re', '-framerate', '22', '-s', '1280x720', '-pix_fmt', 'rgba', '-f', 'rawvideo', '-i', '-', '-f', 's16le', '-ar', '22500', '-i', '/tmp/audio', '-preset', ultrafast', '-pix_fmt', 'rgba', '-b:v', '2500', '-s', 'hd720', '-r', '25', '-g', '50', '-crf', '20', '-f', 'flv', 'rtmp://xxx' ]
  
  
  
  pipe = sp.Popen(command, stdin=sp.PIPE) 

  Then I send my frames to stdin from within my main while True: loop.

  The problem I run into with this strategy is I can’t figure out how to shove audio into FFMPEG from within Python without blocking the pipe. After hours of research, I am pretty confident I can’t use the pipe to send the audio along with the frames. I thought the named pipe was my solution (which works running Espeak outside of Python), but it blocks Python until the Espeak is done... so no good.

  I assume I need threading for multiprocessing, but I cannot figure out from the official documentation or any other resources as to how I can solve my problem with it.

  The ['-f', 's16le', '-ar', '22500', '-i', '/tmp/audio'] are settings that work if I run espeak from a separate terminal with espeak 'some text' --stdout > /tmp/audio.

  I am using Centos 7, Python 2.7, pygame, the latest build of FFMPEG,

• How exactly does this Jaccard distance logic (get_jaccarddist) in FFmpeg work ?

  23 mars 2024, par stilloo

  I see this C code in FFmpeg source signature_lookup file for Jaccard distance in method get_jaccarddist.

  


  If you see in the code below that is calculating for 5 BagOfWords.

  


  Now for two BagOfWords with say nothing in common intersection would be 0, that means jaccarddist would be 0, so ideally its a bad pair but this if condition jaccarddist >= sc->thworddist, would be false isn't it but we want it to be true as its bad pair ?

  


  What are the default values of sc->thworddist ?

  


  Also surprised why jaccarddist is int and not float/double ?

  


  /**
 * calculates the jaccard distance and evaluates a pair of coarse signatures as good
 * @return 0 if pair is bad, 1 otherwise
 */
static int get_jaccarddist(SignatureContext *sc, CoarseSignature *first, CoarseSignature *second)
{
    int jaccarddist, i, composdist = 0, cwthcount = 0;
    for (i = 0; i < 5; i++) {
        if ((jaccarddist = intersection_word(first->data[i], second->data[i])) > 0) {
            jaccarddist /= union_word(first->data[i], second->data[i]);
        }
        if (jaccarddist >= sc->thworddist) {
            if (++cwthcount > 2) {
                /* more than half (5/2) of distances are too wide */
                return 0;
            }
        }
        composdist += jaccarddist;
        if (composdist > sc->thcomposdist) {
            return 0;
        }
    }
    return 1;
}