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• H264 decompression/decomposition into JPG - quality issues

  5 juin 2013, par Respectech

  I'm trying to decode a 1920x1080 30fps h264 stream. Individual frames look outstanding in VLC media player (pausing the playback), but when I decode using avconv (ffmpeg has been deprecated and replaced by avconv), the frame quality is really poor by comparison (my primary complaint is blockiness).

  Here's how I am calling avconv :

  avconv -i video.h264 -s 1920x1080 -f image2 temp/images/video-%03d.jpg

  Is there a jpg output setting for avconv ? I read what I suspected were the salient parts of the avconv documentation (namely, http://libav.org/avconv.html#image2-1), and couldn't find any way to specify the output jpg quality.

  In addition, it appears avconv reads the entire stream before it starts decoding it, so if the stream is in progress, it only decodes to where the stream was when avconv started the decoding process. Is there any way around this ? In other words, if a 10-second-long stream is started at t seconds and avconv is started at t+1 seconds, avconv will only decode 1 second of the stream.

• Converting mkv files to mp4 with ffmpeg-python [closed]

  22 août, par myth0s

  I have a lot of .mkv files that I'm trying to convert to .mp4, so I decided to try and program a solution in python. After a few hours, trying to figure out how to copy the subfolders too, I gave up on it and decided to stick with converting individual subfolders, and then copying them over to another directory.

  


  I've made a simple script, that should convert .mkv files that are in the same folder as the script. However, I keep getting this error :

  


  


  FileNotFoundError : [WinError 2] The system cannot find the file specified

  


  


  Here's my code :

  


  import os
import ffmpeg

start_dir = os.getcwd()

def convert_to_mp4(mkv_file):
    no_extension = str(os.path.splitext(mkv_file))
    with_mp4 = no_extension + ".mp4"
    ffmpeg.input(mkv_file).output(with_mp4).run()
    print("Finished converting {}".format(no_extension))

for path, folder, files in os.walk(start_dir):
    for file in files:
        if file.endswith('.mkv'):
            print("Found file: %s" % file)
            convert_to_mp4(file)
        else:
            pass



  


• avcodec/cuviddec : correctly set key_frame with interlaced content

  11 juin 2021, par stuhlo

  avcodec/cuviddec : correctly set key_frame with interlaced content
  Fixes #9283
  This fixes setting of 'key_frame' flag in AVFrame when input h264 packets represents individual fields of interlaced video.
  
  In this case, pairs of two consecutive fields represents a single decoded picture and have identical 'CurrPicIdx', however, only
  
  the first field is entirely intra-coded and has the flag 'intra_pic_flag' set and the second field was resetting the flag before
  
  it was even read in the function 'cuvid_output_frame'.
  Signed-off-by : Timo Rothenpieler <timo@rothenpieler.org>
  

  • [DH] libavcodec/cuviddec.c