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• How to determine how much of a video stream buffer is filled ?

  17 août 2018, par jjulianf

  On my Ubuntu machine, I am encoding a video with the x265 codec using ffmpeg.
  Then I want to stream the video from a server to a client.

  Since the available bandwidth is limited in specific scenarios, I want to observe the moment when the transmission is starting to stutter.

  Therefore I want to compare the amount of data being sent at this scenario with the amount of data which is already stored in the buffer (and which was sent a few frames earlier) at the client’s side.

  Is there any way to determine how much data is stored in the buffer of the decoding client ? Maybe some ffmpeg command for it ?

  Since I am playing the stream with the VLC player at the client side, is there a vlc-CLI-command to check the buffer status ?

  It would be perfect if I could get the current fill of the buffer for every second so that I can graph it like this :

• ffmpeg - Determine what parameters

  27 juin 2018, par AdmiralJonB

  I’ve got a video file that I’m trying to determine what parameters I can use to reproduce the encoding with ffmpeg.

  Here’s the ffprobe of the particular stream in question.

  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'video.mp4': Metadata:
  
      major_brand     : isom
  
      minor_version   : 512
  
      compatible_brands: isomiso2avc1mp41
  
      encoder         : Lavf57.51.107   
  
  Duration: 00:05:02.84, start: 0.000000, bitrate: 4324 kb/s
  
      Stream #0:0(und): Video: h264 (Main) (avc1 / 0x31637661), yuvj420p(pc, bt709), 1920x1080 [SAR 1:1 DAR 16:9], 4323 kb/s, 25 fps, 25 tbr, 1200k tbn, 2400k tbc (default)
  
      Metadata:
  
        handler_name    : VideoHandler

  The key part is that I’m noticing that the bitrate is quite low at 4324 kb/s, but this is actually an incredibly high quality video. To approach this sort of quality, I’ve only been able to make videos at 40000 kb/s (which is a huge increase in filesize). I also notice that it mentions yuvj420p which is an image format, but I have no idea what parameters with ffmpeg could produce that image format (if this at all would make a difference).

  Would appreciate any help I can get.

  Edit :

  Here’s the output based on the comment below :

  [STREAM]
  
  index=0
  
  codec_name=h264
  
  codec_long_name=H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10
  
  profile=Main
  
  codec_type=video
  
  codec_time_base=123187/3701760
  
  codec_tag_string=avc1
  
  codec_tag=0x31637661
  
  width=1920
  
  height=1080
  
  coded_width=1920
  
  coded_height=1080
  
  has_b_frames=0
  
  sample_aspect_ratio=1:1
  
  display_aspect_ratio=16:9
  
  pix_fmt=yuvj420p
  
  level=41
  
  color_range=pc
  
  color_space=bt709
  
  color_transfer=bt709
  
  color_primaries=bt709
  
  chroma_location=center
  
  field_order=unknown
  
  timecode=N/A
  
  refs=1
  
  is_avc=true
  
  nal_length_size=4
  
  id=N/A
  
  r_frame_rate=15/1
  
  avg_frame_rate=1850880/123187
  
  time_base=1/15360
  
  start_pts=0
  
  start_time=0.000000
  
  duration_ts=246374
  
  duration=16.039974
  
  bit_rate=13795677
  
  max_bit_rate=N/A
  
  bits_per_raw_sample=8
  
  nb_frames=241
  
  nb_read_frames=N/A
  
  nb_read_packets=N/A
  
  DISPOSITION:default=1
  
  DISPOSITION:dub=0
  
  DISPOSITION:original=0
  
  DISPOSITION:comment=0
  
  DISPOSITION:lyrics=0
  
  DISPOSITION:karaoke=0
  
  DISPOSITION:forced=0
  
  DISPOSITION:hearing_impaired=0
  
  DISPOSITION:visual_impaired=0
  
  DISPOSITION:clean_effects=0
  
  DISPOSITION:attached_pic=0
  
  DISPOSITION:timed_thumbnails=0
  
  TAG:language=und
  
  TAG:handler_name=VideoHandler
  
  [/STREAM]

  Edit 2 :

  Here’s information from mediainfo

  Video
  
  ID                                       : 1
  
  Format                                   : AVC
  
  Format/Info                              : Advanced Video Codec
  
  Format profile                           : Main@L4.1
  
  Format settings, CABAC                   : Yes
  
  Format settings, RefFrames               : 1 frame
  
  Format settings, GOP                     : M=1, N=32
  
  Codec ID                                 : avc1
  
  Codec ID/Info                            : Advanced Video Coding
  
  Duration                                 : 5 min 2 s
  
  Bit rate                                 : 4 323 kb/s
  
  Width                                    : 1 920 pixels
  
  Height                                   : 1 080 pixels
  
  Display aspect ratio                     : 16:9
  
  Frame rate mode                          : Constant
  
  Frame rate                               : 25.000 FPS
  
  Color space                              : YUV
  
  Chroma subsampling                       : 4:2:0
  
  Bit depth                                : 8 bits
  
  Scan type                                : Progressive
  
  Bits/(Pixel*Frame)                       : 0.083
  
  Stream size                              : 156 MiB (100%)
  
  Color range                              : Full
  
  Color primaries                          : BT.709
  
  Transfer characteristics                 : BT.709
  
  Matrix coefficients                      : BT.709

• How can I determine if a codec / container combination is compatible with FFmpeg ?

  26 juin 2023, par Dan

  I'm looking at re-muxing some containers holding audio and video such that I extract the best, first audio stream, and store it in a new container where e.g. only the audio stream is present.

  



  The output context for FFmpeg is created like so :

  



  AVFormatContext* output_context = NULL;
avformat_alloc_output_context2( &output_context, NULL, "mp4", NULL );


  



  I have a shortlist of acceptable outputs, e.g. MP4, M4A, etc … essentially those that are readable by Apple's Audio File Services :

  



  kAudioFileAIFFType              = 'AIFF',
kAudioFileAIFCType              = 'AIFC',
kAudioFileWAVEType              = 'WAVE',
kAudioFileSoundDesigner2Type    = 'Sd2f',
kAudioFileNextType              = 'NeXT',
kAudioFileMP3Type               = 'MPG3',   // mpeg layer 3
kAudioFileMP2Type               = 'MPG2',   // mpeg layer 2
kAudioFileMP1Type               = 'MPG1',   // mpeg layer 1
kAudioFileAC3Type               = 'ac-3',
kAudioFileAAC_ADTSType          = 'adts',
kAudioFileMPEG4Type             = 'mp4f',
kAudioFileM4AType               = 'm4af',
kAudioFileM4BType               = 'm4bf',
kAudioFileCAFType               = 'caff',
kAudioFile3GPType               = '3gpp',
kAudioFile3GP2Type              = '3gp2',
kAudioFileAMRType               = 'amrf'


  



  My question is this : is there an easy API in FFmpeg that can be leveraged to choose a compatible output container given the codec the audio stream is in ?