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• opusdsp : adjust and optimize C function to match assembly

  15 août 2019, par Lynne

  opusdsp : adjust and optimize C function to match assembly
  The C and asm versions behaved differently _outside_ of the codec.
  The C version returned pre-multiplied 'state' for the next execution
  
  to use right away, while the assembly version outputted non-multiplied
  
  'state' for the next execution to multiply to save instructions.
  
  Since the initial state when initialized or seeking is always 0,
  
  and since C and asm versions were never mixed, there was no issue.
  However, comparing outputs directly in checkasm doesn't work without
  
  dividing the initial state by CELT_EMPH_COEFF and multiplying the
  
  returned state by CELT_EMPH_COEFF for the assembly function.
  Since its actually faster to do this in C as well, copy the behavior the
  
  asm versions use. As a reminder, the initial state 0 is divided by
  
  CELT_EMPH_COEFF on seek and init (just in case in the future this is
  
  changed, its technically more correct to init with CELT_EMPH_COEFF than 0,
  
  however when seeking this will result in more audiable pops, unlike with 0
  
  where the output gets in sync over a few samples).
  

  • [DH] libavcodec/opus_celt.c
  • [DH] libavcodec/opusdsp.c

• avcodec/omx : Fix handling of fragmented buffers

  17 janvier 2019, par Dave Stevenson

  avcodec/omx : Fix handling of fragmented buffers
  See https://trac.ffmpeg.org/ticket/7687
  If an encoded frame is returned split over two or more
  
  IL buffers due to the size, then there is a race between
  
  whether get_buffer will fail, return NULL, and a truncated
  
  frame is passed on, or IL will return the remaining part
  
  of the encoded frame.
  
  If get_buffer returns NULL, part of the frame is left behind
  
  in the codec, and will be collected on the next call. That
  
  then leaves a frame stuck in the codec. Repeat enough times
  
  and the codec FIFO is full, and the pipeline stalls.
  A performance improvement in the Raspberry Pi firmware means
  
  that the timing has changed, and now frequently drops into the
  
  case where get_buffer returns NULL.
  Add code such that should a buffer be received without
  
  OMX_BUFFERFLAG_ENDOFFRAME that get_buffer is called with wait
  
  set, so we wait for the remainder of the frame.
  
  This code has been made conditional on the Pi build in case
  
  other IL implementations don't handle ENDOFFRAME correctly.
  Signed-off-by : Dave Stevenson <dave.stevenson@raspberrypi.org>
  
  Signed-off-by : Aman Gupta <aman@tmm1.net>
  
  Signed-off-by : Martin Storsjö <martin@martin.st>
  

  • [DH] libavcodec/omx.c

• Taking care of silent priming frames converting mp4 to ts ?

  13 février 2019, par keepitterron

  videoOutputSettings = [
  
    AVVideoCodecKey: AVVideoCodecH264,
  
    AVVideoWidthKey: width,
  
    AVVideoHeightKey: height,
  
    AVVideoCompressionPropertiesKey: [
  
      AVVideoAverageBitRateKey: avgBitRate,
  
      AVVideoExpectedSourceFrameRateKey: fps,
  
      AVVideoProfileLevelKey: AVVideoProfileLevelH264BaselineAutoLevel
  
    ]
  
  ]
  
  audioOutputSettings = [
  
    AVFormatIDKey: kAudioFormatMPEG4AAC,
  
    AVSampleRateKey: 44100,
  
    AVNumberOfChannelsKey: 2
  
  ]

  I record a video + audio with AVCaptureSession (screen, camera and mic in OSX) and i encode it with AVAssetWriter (AVFileType.mp4), swapping the writers every 6 seconds.
  Every time a new part is written, a nodeJS app will be notified and using ffmpeg will convert it to ts with

  ffmpeg -y -i generatedFile.mp4 -c copy -copyts -muxdelay 0 -muxpreload 0 outputFile.ts

  I’ll manually write a m3u8 looking like :

  #EXTM3U
  
  #EXT-X-VERSION:3
  
  #EXT-X-TARGETDURATION:7
  
  #EXT-X-MEDIA-SEQUENCE:0
  
  #EXT-X-PLAYLIST-TYPE:VOD
  
  #EXTINF:6.140227,
  
  11214532343c4cae953d45e94a1660ea-0.ts
  
  #EXTINF:6.284218,
  
  11214532343c4cae953d45e94a1660ea-1.ts
  
  #EXTINF:6.099999999999998,
  
  11214532343c4cae953d45e94a1660ea-2.ts
  
  #EXTINF:6.133333,
  
  11214532343c4cae953d45e94a1660ea-3.ts
  
  #EXTINF:6.133333,
  
  11214532343c4cae953d45e94a1660ea-4.ts
  
  #EXTINF:6.100000000000001,
  
  11214532343c4cae953d45e94a1660ea-5.ts
  
  #EXTINF:6.133333,
  
  11214532343c4cae953d45e94a1660ea-6.ts
  
  #EXTINF:6.199999999999996,
  
  11214532343c4cae953d45e94a1660ea-7.ts
  
  #EXTINF:6.0666670000000025,
  
  11214532343c4cae953d45e94a1660ea-8.ts
  
  #EXT-X-ENDLIST

  The issue is : I have audio gaps between parts and I believe is AAC’s priming frames not being handled correctly.
  Am I correct in assuming so ?

  example file

  ❯ afinfo 11.mp4
  
  File:           11.mp4
  
  File type ID:   mp4f
  
  Num Tracks:     1
  
  ----
  
  Data format:     2 ch,  44100 Hz, 'aac ' (0x00000000) 0 bits/channel, 0 bytes/packet, 1024 frames/packet, 0 bytes/frame
  
                  no channel layout.
  
  estimated duration: 6.128617 sec
  
  audio bytes: 87558
  
  audio packets: 266
  
  bit rate: 113407 bits per second
  
  packet size upper bound: 401
  
  maximum packet size: 401
  
  audio data file offset: 577163
  
  optimized
  
  audio 270272 valid frames + 2112 priming + 0 remainder = 272384
  
  format list:
  
  [ 0] format:      2 ch,  44100 Hz, 'aac ' (0x00000000) 0 bits/channel, 0 bytes/packet, 1024 frames/packet, 0 bytes/frame
  
  Channel layout: Stereo (L R)
  
  ----

  example file

  ❯ ffprobe -v error -show_format -show_streams 1.mp4
  
  [STREAM]
  
  index=0
  
  codec_name=h264
  
  codec_long_name=H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10
  
  profile=Baseline
  
  codec_type=video
  
  codec_time_base=1/60
  
  codec_tag_string=avc1
  
  codec_tag=0x31637661
  
  width=1920
  
  height=1080
  
  coded_width=1920
  
  coded_height=1088
  
  has_b_frames=0
  
  sample_aspect_ratio=1:1
  
  display_aspect_ratio=16:9
  
  pix_fmt=yuv420p
  
  level=40
  
  color_range=tv
  
  color_space=bt709
  
  color_transfer=bt709
  
  color_primaries=bt709
  
  chroma_location=bottom
  
  field_order=unknown
  
  timecode=N/A
  
  refs=1
  
  is_avc=true
  
  nal_length_size=4
  
  id=N/A
  
  r_frame_rate=30/1
  
  avg_frame_rate=30/1
  
  time_base=1/600
  
  start_pts=3600
  
  start_time=6.000000
  
  duration_ts=7260
  
  duration=12.100000
  
  bit_rate=4227137
  
  max_bit_rate=N/A
  
  bits_per_raw_sample=8
  
  nb_frames=183
  
  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:creation_time=2019-02-13T13:21:51.000000Z
  
  TAG:language=und
  
  TAG:handler_name=Core Media Video
  
  [/STREAM]
  
  [STREAM]
  
  index=1
  
  codec_name=aac
  
  codec_long_name=AAC (Advanced Audio Coding)
  
  profile=LC
  
  codec_type=audio
  
  codec_time_base=1/44100
  
  codec_tag_string=mp4a
  
  codec_tag=0x6134706d
  
  sample_fmt=fltp
  
  sample_rate=44100
  
  channels=2
  
  channel_layout=stereo
  
  bits_per_sample=0
  
  id=N/A
  
  r_frame_rate=0/0
  
  avg_frame_rate=0/0
  
  time_base=1/44100
  
  start_pts=272991
  
  start_time=6.190272
  
  duration_ts=545352
  
  duration=12.366259
  
  bit_rate=115688
  
  max_bit_rate=128000
  
  bits_per_raw_sample=N/A
  
  nb_frames=269
  
  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:creation_time=2019-02-13T13:21:51.000000Z
  
  TAG:language=und
  
  TAG:handler_name=Core Media Audio
  
  [/STREAM]
  
  [FORMAT]
  
  filename=1.mp4
  
  nb_streams=2
  
  nb_programs=0
  
  format_name=mov,mp4,m4a,3gp,3g2,mj2
  
  format_long_name=QuickTime / MOV
  
  start_time=6.000000
  
  duration=12.366259
  
  size=3317034
  
  bit_rate=2145860
  
  probe_score=100
  
  TAG:major_brand=mp42
  
  TAG:minor_version=1
  
  TAG:compatible_brands=mp41mp42isom
  
  TAG:creation_time=2019-02-13T13:21:51.000000Z
  
  [/FORMAT]

  Is there a way I can generate ts files with the encoder delay being taken care of ?