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• Audioqueue try to read ADPCM sound

  4 septembre 2013, par Kamax

  I try to read a .asf stream with FFMPEG and the audio part is ADPCM IMA WAV codec.

  The sound i hear when i hear something is only noise. I suppose my AudioStreamBasicDescription are wrong. How can i get the correct values ?

  From ffprobe i have this :

  [STREAM]
  
  index=1
  
  codec_name=adpcm_ima_wav
  
  codec_long_name=ADPCM IMA WAV
  
  codec_type=audio
  
  codec_time_base=1/8000
  
  codec_tag_string=[17][0][0][0]
  
  codec_tag=0x0011
  
  sample_rate=8000.000000 
  
  channels=1
  
  bits_per_sample=4
  
  r_frame_rate=0/0
  
  avg_frame_rate=250/41
  
  time_base=1/1000
  
  start_time=0.000000 
  
  duration=N/A
  
  [/STREAM]

  and

  Stream #0.1: Audio: adpcm_ima_wav, 8000 Hz, 1 channels, s16, 32 kb/s

  my code for the moment is :

  asbd.mSampleRate = 8000;
  
  asbd.mFormatID = kAudioFormatAppleIMA4;
  
  asbd.mBytesPerPacket = 34;
  
  asbd.mFramesPerPacket = 64;
  
  asdb.mbitsPerChannel = 1;

  All the rest is to 0 (flags, byte per frame, bits per channel, reserved).

  Edit :

  I just find that the codec code 17 is maybe for kAudioFormatDVIIntelIMA and not kAudioFormatAppleIMA4. Can someone confirm this ?

  This is from ffprobe :

  [PACKET]
  
  codec_type=audio
  
  stream_index=1
  
  pts=11200
  
  pts_time=11.200000 
  
  dts=11200
  
  dts_time=11.200000 
  
  duration=164
  
  duration_time=0.164000 
  
  size=656.000000 
  
  pos=1171105
  
  flags=K
  
  [/PACKET]

  Is the size 656 for mBytesperpacket ?

  With this value and the half 328 for mFramesPerPacket i can hear something but it's not continuous and has a lot of noise.

  Please help !

• Modify H.264 Level in MP4 stream

  25 mars 2013, par d33pika

  I have 1000+ videos with wrong Level information, and hence do not play on some devices. They are H.264 baseline with aac audio in mp4 container. I want to correct them but avoid re-encoding. Am I right in assuming that this is possible and will be faster ? How do I identify the level_idc bits in the streams ? Will all streams have them in the same location ? I expect this to be in just one place in the stream, is this assumption correct ?
  Update : I came across a windows executable link that claims to do this. I want to be able to do this commandline on unix, so I can script it.

  More Updates : As per Roman's answer below. I dug up MP4 syntax and found that Profile and Level information are part of avcC atom under stsd. I could see that level was set to 1E, I corrected it to 1F. Before :

  61 76 63 43 01 42 C0 1E FF E1 00 19 67 42 C0 1E
D9

  After :

  61 76 63 43 01 42 C0 1F FF E1 00 19 67 42 C0 1E
D9

  with that the MediaInfo changed to :

  Video
  
  ID                                       : 1
  
  Format                                   : AVC
  
  Format/Info                              : Advanced Video Codec
  
  Format profile                           : Baseline@L3.0
  
  Format settings, CABAC                   : No
  
  Format settings, ReFrames                : 3 frames
  
  Muxing mode                              : Container profile=Baseline@3.1
  
  Codec ID                                 : avc1
  
  Codec ID/Info                            : Advanced Video Coding
  
  Duration                                 : 1mn 4s
  
  Bit rate                                 : 3 000 Kbps
  
  Width                                    : 1 280 pixels
  
  Height                                   : 720 pixels
  
  Display aspect ratio                     : 16:9
  
  Frame rate mode                          : Constant
  
  Frame rate                               : 30.000 fps
  
  Color space                              : YUV
  
  Chroma subsampling                       : 4:2:0
  
  Bit depth                                : 8 bits
  
  Scan type                                : Progressive
  
  Bits/(Pixel*Frame)                       : 0.109
  
  Stream size                              : 22.7 MiB (92%)
  
  Writing library                          : x264 core 120 r2151 a3f4407
  
  Encoding settings                        : cabac=0 / ref=3 / deblock=1:0:0 / analyse=0x1:0x111 / me=hex / subme=7 / psy=1 / psy_rd=1.00:0.00 / mixed_ref=1 / me_range=16 / chroma_me=1 / trellis=1 / 8x8dct=0 / cqm=0 / deadzone=21,11 / fast_pskip=1 / chroma_qp_offset=-2 / threads=12 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 / bluray_compat=0 / constrained_intra=0 / bframes=0 / weightp=0 / keyint=250 / keyint_min=25 / scenecut=40 / intra_refresh=0 / rc_lookahead=40 / rc=abr / mbtree=1 / bitrate=3000 / ratetol=1.0 / qcomp=0.60 / qpmin=0 / qpmax=69 / qpstep=4 / ip_ratio=1.40 / aq=1:1.00 

  It introduced a Muxing mode parameter with level 3.1 but alas this stream did not play on the device either. How do I correct the level indicated in Format Profile Is this possible without re-encoding ?

• ffmpeg - scaling and stacking 2 videos ?

  25 mai 2016, par Gambit2007

  I have 2 inputs and i want to scale, crop and put them on top of each other at the same time. My command should look something like this :

  ffmpeg -i input1 -i input2 -filter_complex crop=10000:5000:1000:0,scale=3840:1536 vstack output.mp4

  I know i need to use chaining (?) but i tried to look it up online and couldn’t really get it to work.

  So what would be the correct syntax the scale and crop both inputs and then put them vertically on top of each other while using ’-filter_complex’ only once ?

  Thanks !