Recherche avancée

Sur d’autres sites (9208)

• Don’t use expressions with side effects in macro parameters

  28 juillet 2016, par Martin Storsjö

  Don’t use expressions with side effects in macro parameters
  AV_WB32 can be implemented as a macro that expands its parameters
  
  multiple times (in case AV_HAVE_FAST_UNALIGNED isn’t set and the
  
  compiler doesn’t support GCC attributes) ; make sure not to read
  
  multiple times from the source in this case.
  Signed-off-by : Martin Storsjö <martin@martin.st>
  

  • [DBH] libavcodec/dxv.c
  • [DBH] libavformat/xmv.c

• .MKV Video File not playing on Azure Kinect Viewer

  17 avril 2023, par Ashutosh Singla

  I have a video file that contains 4 streams, 3 videos streams and one steam for metadata. I want to extract these streams first with metadata and then want to combine them together with metadata. I would like to play the video on Azure Kinect Viewer so that I can see if I am doing anything wrong while extracting and copying the stream.

  


  Original Stream Info :

  


  Input #0, matroska,webm, from 'output_master.mkv':
Metadata:
title           : Azure Kinect
encoder         : libmatroska-1.4.9
creation_time   : 2021-05-20T12:11:15.000000Z
K4A_DEPTH_DELAY_NS: 0
K4A_WIRED_SYNC_MODE: MASTER
K4A_COLOR_FIRMWARE_VERSION: 1.6.110
K4A_DEPTH_FIRMWARE_VERSION: 1.6.79
K4A_DEVICE_SERIAL_NUMBER: 000123102712
K4A_START_OFFSET_NS: 298800000
Duration: 00:00:40.03, start: 0.000000, bitrate: 480934 kb/s

Stream #0:0(eng): Video: mjpeg (Baseline) (MJPG / 0x47504A4D), yuvj422p(pc, bt470bg/unknown/unknown), 2048x1536, SAR 1:1 DAR 4:3, 30 fps, 30 tbr, 1000k tbn (default)
Metadata:
  title           : COLOR
  K4A_COLOR_TRACK : 14499183330009048
  K4A_COLOR_MODE  : MJPG_1536P
Stream #0:1(eng): Video: rawvideo (b16g / 0x67363162), gray16be, 640x576, SAR 1:1 DAR 10:9, 30 fps, 30 tbr, 1000k tbn (default)
Metadata:
  title           : DEPTH
  K4A_DEPTH_TRACK : 429408169412322196
  K4A_DEPTH_MODE  : NFOV_UNBINNED
Stream #0:2(eng): Video: rawvideo (b16g / 0x67363162), gray16be, 640x576, SAR 1:1 DAR 10:9, 30 fps, 30 tbr, 1000k tbn (default)
Metadata:
  title           : IR
  K4A_IR_TRACK    : 194324406376800992
  K4A_IR_MODE     : ACTIVE
Stream #0:3: Attachment: none
Metadata:
  filename        : calibration.json
  mimetype        : application/octet-stream
  K4A_CALIBRATION_FILE: calibration.json


  


  I am using the below command to extract Stream #0:0, Stream #0:1, and Stream #0:2 by changing map 0:X.

  


  ffmpeg -i output_master.mkv -c copy -allow_raw_vfw 1 -map 0:0 temp_0.mkv 


  


  To extract the configuration file from the video and store them in calibration.json, I am using the command below :

  


  ffmpeg -dump_attachment:3 calibration.json -i output_master.mkv


  


  To combine the streams with configuration file using FFmpeg, I am using the command below :

  


  ffmpeg -i temp_0.mkv -i temp_1.mkv -i temp_2.mkv -c copy -map 0:0 -map 1:0 -map 2:0 -allow_raw_vfw 1 -attach calibration.json -metadata:s:3 mimetype=application/octet-stream out.mkv


  


  Reconstrcuted Stream Info :

  


    Could not find codec parameters for stream 3 (Attachment: none): unknown codec
  Consider increasing the value for the 'analyzeduration' (0) and 'probesize' (5000000) options

  Input #0, matroska,webm, from '.\out.mkv':
  Metadata:
  title           : Azure Kinect
  K4A_COLOR_FIRMWARE_VERSION: 1.6.110
  K4A_DEPTH_FIRMWARE_VERSION: 1.6.79
  K4A_DEVICE_SERIAL_NUMBER: 000123102712
  K4A_START_OFFSET_NS: 298800000
  K4A_DEPTH_DELAY_NS: 0
  K4A_WIRED_SYNC_MODE: MASTER
  ENCODER         : Lavf60.3.100
  Duration: 00:00:40.06, start: 0.000000, bitrate: 480559 kb/s

  Stream #0:0(eng): Video: mjpeg (Baseline), yuvj422p(pc, bt470bg/unknown/unknown), 2048x1536, SAR 1:1 DAR 4:3, 30 fps, 30 tbr, 1k tbn (default)
  Metadata:
  title           : COLOR
  K4A_COLOR_TRACK : 14499183330009048
  K4A_COLOR_MODE  : MJPG_1536P
  DURATION        : 00:00:40.029000000

  Stream #0:1(eng): Video: rawvideo, rgb555le, 640x576, SAR 1:1 DAR 10:9, 30 fps, 30 tbr, 1k tbn (default)
  Metadata:
  title           : DEPTH
  K4A_DEPTH_TRACK : 429408169412322196
  K4A_DEPTH_MODE  : NFOV_UNBINNED
  DURATION        : 00:00:40.062000000

  Stream #0:2(eng): Video: rawvideo, rgb555le, 640x576, SAR 1:1 DAR 10:9, 30 fps, 30 tbr, 1k tbn (default)
  Metadata:
  title           : IR
  K4A_IR_TRACK    : 194324406376800992
  K4A_IR_MODE     : ACTIVE
  DURATION        : 00:00:40.062000000

  Stream #0:3: Attachment: none
  Metadata:
  filename        : calibration.json
  mimetype        : application/octet-stream


  


  However, I can not play the video on Azure Kinect Viewer, It displays failed to open recording.

  


  Any help would be appreciated.

  


• Video files recorded in Google Chrome have stuttering audio

  4 juin 2018, par maxpaj

  Background

  I’m developing a platform where users can record videos of themselves or their screen and send them as video messages to customers / clients.

  I have limited users to only using my application with Google Chrome and I’m using the MediaRecorder API to record the video data from the users screen or webcamera. The codecs that are used for recording are VP8/OPUS (WEBM container).

  I need the videos to run in as many browsers as possible, so I’m using a 3rd party service to transcode videos from whatever format I’m getting from the users to a H.265/AAC MP4 container (caniuse MPEG-4/H.264).

  Issue

  Lately I’ve seen that some videos recorded on Mac OSX machines have the video and audio out of sync or that the video and audio stutters, depending on which player I’m using. I call these video files corrupt, for lack of a better word. Playing a corrupt file in Google Chrome renders smooth playing audio. Playing the video in VLC on my Windows machine renders stuttering audio.

  When I run the corrupt video files through the transcoding service I get video files with stuttering audio, no matter which player I’m using.

  This is an unwanted result and pretty much unacceptable since the audio needs to be smooth in order for the recipient of a video to not be bothered with the quality.

  Debugging

  According to the transcoding service support, this happens because of their mechanisms that try to sync up the audio and video from the corrupt file :

  Inspecting our encoding logs, I’ve noticed the following kind of
  warnings :

  [2018-05-16 14:08:38.009] [pcm_s16le @ 0x1d608c0] pcm_encode_frame :
  filling in for 5856 missing samples (122 ms) before pts 40800 to
  correct sync ! [2018-05-16 14:08:38.009] [pcm_s16le @ 0x1d608c0]
  pcm_encode_frame : dropping 2880 samples (60 ms) at pts 43392 to help
  correct sync to -3168 samples (-66 ms) !

  The problem here comes from the way that the audio in the original
  source file is encoded.

  -

  you should ensure that the audio is not out of sync (audio timestamps
  are correct) in your source file before submitting the job

  Running a corrupt file through ffmpeg on my own machine, re-encoding with the same codecs, produces the same kind of stuttering video. The logs produce an alarming amount of errors. Here is a sample of the log output :

  [libopus @ 0000029938e24d80] Queue input is backward in timeitrate= 194.8kbits/s dup=0 drop=5 speed=0.31x
  
  [webm @ 0000029938e09b00] Non-monotonous DTS in output stream 0:1; previous: 15434, current: 15394; changing to 15434. This may result in incorrect timestamps in the output file.
  
  [webm @ 0000029938e09b00] Non-monotonous DTS in output stream 0:1; previous: 15434, current: 15414; changing to 15434. This may result in incorrect timestamps in the output file.
  
  [libopus @ 0000029938e24d80] Queue input is backward in timeitrate= 193.3kbits/s dup=0 drop=5 speed=0.309x
  
  [webm @ 0000029938e09b00] Non-monotonous DTS in output stream 0:1; previous: 15539, current: 15499; changing to 15539. This may result in incorrect timestamps in the output file.
  
  [webm @ 0000029938e09b00] Non-monotonous DTS in output stream 0:1; previous: 15539, current: 15519; changing to 15539. This may result in incorrect timestamps in the output file.
  
  [libopus @ 0000029938e24d80] Queue input is backward in timeitrate= 192.0kbits/s dup=0 drop=5 speed=0.308x
  
  [webm @ 0000029938e09b00] Non-monotonous DTS in output stream 0:1; previous: 15667, current: 15627; changing to 15667. This may result in incorrect timestamps in the output file.
  
  [webm @ 0000029938e09b00] Non-monotonous DTS in output stream 0:1; previous: 15667, current: 15647; changing to 15667. This may result in incorrect timestamps in the output file.
  
  [libopus @ 0000029938e24d80] Queue input is backward in time

  I tried running the same inputs through another transcoding service and those outputs worked a lot better - video was still stuttering but the audio played smoothly, which is more important to the use case of my application.

  To my knowledge, this have so far only occurred for users on Mac OSX machines.

  Questions

  1. Is there anything I can do to have the files work better ? Or is this entirely a consequence of how encoding of video and audio in Google Chrome works ?

  2. One step in the right direction would be to just be able to detect when the video is corrupt. How can I do that ?