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• avformat/tls_schannel : immediately return decrypted data if available

  12 mai 2020, par Jan Ekström

  avformat/tls_schannel : immediately return decrypted data if available
  Until now, we would have only attempted to utilize already decrypted
  
  data if it was enough to fill the size of buffer requested, that could
  
  very well be up to 32 kilobytes.
  With keep-alive connections this would just lead to recv blocking
  
  until rw_timeout had been reached, as the connection would not be
  
  officially closed after each transfer. This would also lead to a
  
  loop, as such timed out I/O request would just be attempted again.
  By just returning the available decrypted data, keep-alive based
  
  connectivity such as HLS playback is fixed with schannel.
  

  • [DH] libavformat/tls_schannel.c

• OpenCV : FFMPEG : tag 0x00000021/' !???' is not found (format 'mp4 / MP4 (MPEG-4 Part 14)')'

  10 juin 2020, par Hepo8421

  I got error when trying to run a python script. Iam trying to make a project based on pyimagesearch tutorial.

  



  Code :
In first script :

  



  filename = tempVideo.path[tempVideo.path.rfind("/") + 1:]
    s3.upload_file(tempVideo.path, self.conf["s3_bucket"],
        filename, ExtraArgs={"ACL": "public-read",
        "ContentType": "video/mp4"})


  



  In main script :

  



  tempVideo = TempFile(ext=".mp4")
    writer = cv2.VideoWriter(tempVideo.path, 0x21, 30, (W, H),
        True)


  



  Error I recieved :

  



  OpenCV: FFMPEG: tag 0x00000021/'!???' is not found (format 'mp4 / MP4 (MPEG-4 Part 14)')'
Exception in thread Thread-4:
Traceback (most recent call last):
  File "/usr/lib/python3.7/threading.py", line 917, in _bootstrap_inner
    self.run()
  File "/usr/lib/python3.7/threading.py", line 865, in run
    self._target(*self._args, **self._kwargs)
  File "/home/pi/Desktop/pi-security-camera/pyimagesearch/notifications/twilionotifier.py", line 27, in _send
    "ContentType": "video/mp4"})
  File "/home/pi/.virtualenvs/cv/lib/python3.7/site-packages/boto3/s3/inject.py", line 131, in upload_file
    extra_args=ExtraArgs, callback=Callback)
  File "/home/pi/.virtualenvs/cv/lib/python3.7/site-packages/boto3/s3/transfer.py", line 279, in upload_file
    future.result()
  File "/home/pi/.virtualenvs/cv/lib/python3.7/site-packages/s3transfer/futures.py", line 106, in result
    return self._coordinator.result()
  File "/home/pi/.virtualenvs/cv/lib/python3.7/site-packages/s3transfer/futures.py", line 265, in result
    raise self._exception
  File "/home/pi/.virtualenvs/cv/lib/python3.7/site-packages/s3transfer/tasks.py", line 255, in _main
    self._submit(transfer_future=transfer_future, **kwargs)
  File "/home/pi/.virtualenvs/cv/lib/python3.7/site-packages/s3transfer/upload.py", line 549, in _submit
    upload_input_manager.provide_transfer_size(transfer_future)
  File "/home/pi/.virtualenvs/cv/lib/python3.7/site-packages/s3transfer/upload.py", line 237, in provide_transfer_size
    transfer_future.meta.call_args.fileobj))
  File "/home/pi/.virtualenvs/cv/lib/python3.7/site-packages/s3transfer/utils.py", line 245, in get_file_size
    return os.path.getsize(filename)
  File "/usr/lib/python3.7/genericpath.py", line 50, in getsize
    return os.stat(filename).st_size
FileNotFoundError: [Errno 2] No such file or directory: './/13675f07-ecec-48ae-97bf-32109eb3ed7d.mp4'


  



  Thanks for advices :)

  


• Matching a specific media format with ffmpeg/avconv

  5 mai 2020, par Markus A.

  I need to encode a video from static images in such a way that it format-matches another one so I can splice the video streams together.

  



  Here is the mediainfo of the file I'm trying to match :

  



  Video
Format                                   : AVC
Format/Info                              : Advanced Video Codec
Format profile                           : Baseline@L3.1
Format settings, CABAC                   : No
Format settings, ReFrames                : 1 frame
Codec ID                                 : 7
Duration                                 : 2mn 46s
Bit rate                                 : 1 614 Kbps
Width                                    : 1 280 pixels
Height                                   : 720 pixels
Display aspect ratio                     : 16:9
Frame rate mode                          : Variable
Standard                                 : NTSC
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 8 bits
Scan type                                : Progressive
Stream size                              : 32.0 MiB (87%)
Color primaries                          : BT.601 PAL
Transfer characteristics                 : BT.601
Matrix coefficients                      : BT.601


  



  So far, what I have been able to come up with is the following :

  



  avconv -f image2 -framerate 1.2 -i loop_%d.tif -c:v libx264 -preset veryslow -profile:v baseline -level:v 31 -b:v 1614K -refs 1 loop.flv


  



  This gets me to :

  



  Video
Format                                   : AVC
Format/Info                              : Advanced Video Codec
Format profile                           : Baseline@L3.1
Format settings, CABAC                   : No
Format settings, ReFrames                : 1 frame
Codec ID                                 : 7
Duration                                 : 2s 917ms
Bit rate                                 : 1 614 Kbps
Width                                    : 1 280 pixels
Height                                   : 720 pixels
Display aspect ratio                     : 16:9
Frame rate mode                          : Constant
Frame rate                               : 1.200 fps
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 8 bits
Scan type                                : Progressive
Bits/(Pixel*Frame)                       : 1.459
Stream size                              : 575 KiB
Writing library                          : x264 core 142 r2431 a5831aa
Encoding settings                        : cabac=0 / ref=1 / deblock=1:0:0 / analyse=0x1:0x131 / me=umh / subme=10 / psy=1 / psy_rd=1.00:0.00 / mixed_ref=0 / me_range=24 / chroma_me=1 / trellis=2 / 8x8dct=0 / cqm=0 / deadzone=21,11 / fast_pskip=1 / chroma_qp_offset=-2 / threads=6 / lookahead_threads=1 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 / bluray_compat=0 / constrained_intra=0 / bframes=0 / weightp=0 / keyint=250 / keyint_min=1 / scenecut=40 / intra_refresh=0 / rc_lookahead=60 / rc=abr / mbtree=1 / bitrate=1614 / ratetol=1.0 / qcomp=0.60 / qpmin=0 / qpmax=69 / qpstep=4 / ip_ratio=1.40 / aq=1:1.00


  



  Which, unfortunately, still isn't good enough as VLC Media Player crashes hard (just closes), logging main error: Failed to compensate for the format changes, removing all filters; main error: Failed to create video converter as soon as the stream splice occurs. I tried splicing another stream in that does have the exact same encoding, and it works fine. I'm also making sure to only splice on key-frames and I am including the NALU containing the AVCDecoderConfigRecord, so I'm pretty sure I'm not doing anything else wrong, especially since a couple other programs are fine with the splice. It's just VLC that expects an even closer match.

  



  Here are things I've tried :

  



  

  • Adding -vsync 2 to get variable frame rate mode. Doesn't change anything.

  


  • Adding -color_primaries bt470bg -color_trc gamma28 -colorspace bt470bg to try to get BT.601 PAL settings (several websites mentioned this). Doesn't change anything.

  


  • Adding -s ntsc to set the standard to NTSC. This also changes the resolution to 720x480 (not OK), and specifying -s 1280x720 in addition gets rid of the NTSC tag again.

  


  



  If anyone knows what flags I need to supply to get closer, that would be super-helpful ! The stream I'm trying to match is encoded on an Android device (it's a live-stream), so I'm assuming it is built using the standard Android MediaCoder framework, in case that helps.