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• ffmpeg how to select the audio channel with the biggest bps ?

  31 octobre 2018, par Kris Roofe

  I have mp4 file with below format,

  $ ffprobe -i 70_1.mp4 -hide_banner
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '70_1.mp4':
 Metadata:
   major_brand     : qt
   minor_version   : 0
   compatible_brands: qt
   creation_time   : 2018-10-30T08:57:38.000000Z
 Duration: 00:13:55.76, start: 0.000000, bitrate: 2246 kb/s
   Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuvj420p(pc, smpte170m/bt709/unknown, progressive), 1440x1920, 2118 kb/s, 58.75 fps, 60 tbr, 600 tbn, 1200 tbc (default)
   Metadata:
     creation_time   : 2018-10-30T08:57:38.000000Z
     handler_name    : Core Media Video
     encoder         : 'avc1'
   Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 2 kb/s (default)
   Metadata:
     creation_time   : 2018-10-30T08:57:38.000000Z
     handler_name    : Core Media Audio
   Stream #0:2(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 119 kb/s (default)
   Metadata:
     creation_time   : 2018-10-30T08:57:38.000000Z
     handler_name    : Core Media Audio

  As the auto channel is special, there is no sound when play in the browser.

  So I use ffmpeg to transfer it with ffmpeg -i 70_1.mp4 -crf 30 -b:a 23k -b:v 96k -threads 4 -map 0:0 -map 0:2 -y ooo.mp4, the generated mp4 file can play in the browser.

  $ ffprobe.exe ooo.mp4 -hide_banner
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'ooo.mp4':
 Metadata:
   major_brand     : isom
   minor_version   : 512
   compatible_brands: isomiso2avc1mp41
   encoder         : Lavf58.17.101
 Duration: 00:13:55.79, start: 0.000000, bitrate: 246 kb/s
   Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuvj420p(pc), 1440x1920, 209 kb/s, 60 fps, 60 tbr, 15360 tbn, 120 tbc (default)
   Metadata:
     handler_name    : Core Media Video
   Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 23 kb/s (default)
   Metadata:
     handler_name    : Core Media Audio

  But there is one issue, I need to process mp4 file with many formats, some with 1 audio channel, some with 2, So I want to know how to select the audio channel with the biggest bps.

• ffpmeg drops last frame when compressing from MP4 to MP4 (libx264)

  28 octobre 2018, par Usoboi

  So, I’m using this code to compress my *mp4 file. I need to get lower quality and decrease bitrate :

  ffmpeg -i input.mp4 -c:v libx264 output.mp4

  The problem is : the last frame of footage is dropped after ffmpeg compression.
  Screenshot is here : screenshot_ffmpeg_drop frame

  I tried to use full preferences I need, but the problem is the same.

  ffmpeg -i input.mp4 -c:v libx264 -vf scale=1280:720 -preset fast -crf 29 -r 25 -c:a copy output.mp4

  logfile during ffmpeg encoding :

  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from ’\input.mp4’ :
  Metadata :
  major_brand : mp42
  minor_version : 0
  compatible_brands : mp42mp41
  creation_time : 2018-10-28T11:06:03.000000Z
  Duration : 00:00:12.76, start : 0.000000, bitrate : 5374 kb/s
  Stream #0:0(eng) : Video : h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709), 1920x1080 [SAR 1:1 DAR 16:9], 5368 kb/s, 25 fps, 25 tbr, 50k tbn, 50 tbc (default)
  Metadata :
  creation_time : 2018-10-28T11:06:03.000000Z
  handler_name : Alias Data Handler
  encoder : AVC Coding

  Stream mapping : Stream #0:0 -> #0:0 (h264 (native) -> h264
  (libx264)) Press [q] to stop, [?] for help [libx264 @
  000002fae8b50780] using SAR=1/1 [libx264 @ 000002fae8b50780] using cpu
  capabilities : MMX2 SSE2Fast SSSE3 SSE4.2 AVX FMA3 BMI2 AVX2 [libx264 @
  000002fae8b50780] profile High, level 3.1 [libx264 @ 000002fae8b50780]
  264 - core 155 r2901 7d0ff22 - H.264/MPEG-4 AVC codec - Copyleft
  2003-2018 - http://www.videolan.org/x264.html - options : cabac=1 ref=2
  deblock=1:0:0 analyse=0x3:0x113 me=hex subme=6 psy=1 psy_rd=1.00:0.00
  mixed_ref=1 me_range=16 chroma_me=1 trellis=1 8x8dct=1 cqm=0
  deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=12
  lookahead_threads=2 sliced_threads=0 nr=0 decimate=1 interlaced=0
  bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=1
  b_bias=0 direct=1 weightb=1 open_gop=0 weightp=1 keyint=250
  keyint_min=25 scenecut=40 intra_refresh=0 rc_lookahead=30 rc=crf
  mbtree=1 crf=29.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40
  aq=1:1.00 Output #0, mp4, to ’\output.mp4’ : Metadata :
  major_brand : mp42
  minor_version : 0
  compatible_brands : mp42mp41
  encoder : Lavf58.17.100
  Stream #0:0(eng) : Video : h264 (libx264) (avc1 / 0x31637661), yuv420p, 1280x720 [SAR 1:1 DAR 16:9], q=-1—1, 25 fps, 12800 tbn, 25
  tbc (default)
  Metadata :
  creation_time : 2018-10-28T11:06:03.000000Z
  handler_name : Alias Data Handler
  encoder : Lavc58.19.104 libx264
  Side data :
  cpb : bitrate max/min/avg : 0/0/0 buffer size : 0 vbv_delay : -1

  frame= 318 fps=127 q=-1.0 Lsize= 855kB time=00:00:12.60 bitrate=
  556.0kbits/s speed=5.05x video:851kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead : 0.534683% [libx264 @
  0000015d5cef0500] frame I:2 Avg QP:26.18 size : 67800 [libx264 @
  0000015d5cef0500] frame P:80 Avg QP:27.93 size : 5439 [libx264 @
  0000015d5cef0500] frame B:236 Avg QP:32.44 size : 1269 [libx264 @
  0000015d5cef0500] consecutive B-frames : 0.9% 0.0% 0.9% 98.1%
  [libx264 @ 0000015d5cef0500] mb I I16..4 : 10.6% 62.5% 26.8% [libx264
  @ 0000015d5cef0500] mb P I16..4 : 0.5% 1.0% 0.2% P16..4 : 36.1%
  5.1% 3.6% 0.0% 0.0% skip:53.6% [libx264 @ 0000015d5cef0500] mb B I16..4 : 0.6% 0.5% 0.0% B16..8 : 22.2% 0.6% 0.0% direct : 2.0%
  skip:74.2% L0:44.9% L1:54.5% BI : 0.6% [libx264 @ 0000015d5cef0500]
  8x8 transform intra:55.0% inter:86.2% [libx264 @ 0000015d5cef0500]
  coded y,uvDC,uvAC intra : 48.1% 54.9% 27.0% inter : 3.2% 5.2% 0.2%
  [libx264 @ 0000015d5cef0500] i16 v,h,dc,p : 19% 56% 10% 15% [libx264 @
  0000015d5cef0500] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu : 19% 25% 18% 5% 6%
  5% 8% 5% 8% [libx264 @ 0000015d5cef0500] i4
  v,h,dc,ddl,ddr,vr,hd,vl,hu : 27% 24% 9% 5% 8% 7% 9% 5% 7%
  [libx264 @ 0000015d5cef0500] i8c dc,h,v,p : 60% 20% 15% 4% [libx264 @
  0000015d5cef0500] Weighted P-Frames : Y:0.0% UV:0.0% [libx264 @
  0000015d5cef0500] ref P L0 : 67.7% 32.3% [libx264 @ 0000015d5cef0500]
  ref B L0 : 80.4% 19.6% [libx264 @ 0000015d5cef0500] ref B L1 : 92.1%
  7.9% [libx264 @ 0000015d5cef0500] kb/s:547.35

• Losing frames when clipping videos with ffmpeg

  9 décembre 2018, par Mark C

  I seem to be losing frames when I clip videos up with ffmpeg.

  Here are the steps I take :

  [Get the Frame number to cut on] -> [turn the frame number into hh:mm:ss.ms format] -> [Run ffmpeg process]

  Here is the code :

  import subprocess
  
  
  
  def frames_to_timecode(frame,frameRate):
  
      '''
  
      Convert frame into a timecode HH:MM:SS.MS
  
      frame = The frame to convert into a time code
  
      frameRate = the frame rate of the video
  
      '''
  
      #convert frames into seconds
  
      seconds = frame / frameRate
  
  
  
      #generate the time code
  
      timeCode = '{h:02d}:{m:02d}:{s:02f}'.format(
  
      h=int(seconds/3600),
  
      m=int(seconds/60%60),
  
      s=seconds%60)
  
  
  
      return timeCode
  
  
  
  frameRate = 24.0
  
  
  
  inputVideo = r"C:\Users\aquamen\Videos\vlc-record-2018-10-23-17h11m11s-SEQ-0200_animatic_v4_20180827_short.mp4"
  
  outputVideo = r"C:\Users\aquamen\Videos\ffmpeg_test_clip001.mp4"
  
  ffmpeg = r"C:\ffmpeg\ffmpeg-20181028-e95987f-win64-static\bin\ffmpeg.exe" 
  
  
  
  endFrame = frames_to_timecode(29,frameRate)
  
  startFrame = frames_to_timecode(10,frameRate)
  
  
  
  subprocess.call([ffmpeg,'-i',inputVideo,'-ss',startFrame,'-to',endFrame,outputVideo])

  Here is a image of the original video and the clipped video with the time codes showing a frame was lost in process. The time code should show 00:01:18:10 instead its 00:01:18:11.