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• How to fix grainy recoding with ffmpeg mp4 x264 ?

  21 mars 2020, par teenserie

  I recorded the audio and video stream from a streaming with ffmpeg. when I go to re-encode the file using libx264, the video in the movements looks bad and grainy as in the image.
  Where did I go wrong ?

  

  this is the code I used

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

  and these are mediainfo of original file

      Metadata:
  
      major_brand     : isom
  
      minor_version   : 1
  
      compatible_brands: isom
  
      creation_time   : 2020-03-19T22:43:32.000000Z
  
    Duration: 00:39:51.99, start: 0.000000, bitrate: 1300 kb/s
  
      Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709), 1280x1080 [SAR 3:2 DAR 16:9], Closed Captions, 1268 kb/s, 59.94 fps, 59.94 tbr, 90k tbn, 59.94 tbc (default)
  
      Metadata:
  
        handler_name    : VideoHandler
  
      Stream #0:1(spa): Audio: aac (HE-AACv2) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 22 kb/s (default)
  
      Metadata:
  
        handler_name    : SoundHandler

  mediainfo of the file recoded

   Metadata:
  
      major_brand     : isom
  
      minor_version   : 512
  
      compatible_brands: isomiso2avc1mp41
  
      encoder         : Lavf58.29.100
  
    Duration: 00:39:51.99, start: 0.000000, bitrate: 7924 kb/s
  
      Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], Closed Captions, 7892 kb/s, 59.94 fps, 59.94 tbr, 60k tbn, 119.88 tbc (default)
  
      Metadata:
  
        handler_name    : VideoHandler
  
      Stream #0:1(spa): Audio: aac (HE-AACv2) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 22 kb/s (default)
  
      Metadata:
  
        handler_name    : SoundHandler

  How can I recode the file without loss of quality ? (sorry for my poor english)

• avcodec/aacenc : Avoid 0 lambda

  28 mai 2021, par Michael Niedermayer

  avcodec/aacenc : Avoid 0 lambda
  Fixes : Ticket8003
  
  Fixes : CVE-2020-20453
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavcodec/aacenc.c

• Losing audio quality when merging multiple videos with FFmpeg

  30 mai 2021, par Charly

  I am trying to merge multiple videos (a few seconds each) into one, using FFmpeg.

  


  Merging all at once

  


  I first tried merging all videos with one FFmpeg command, but it only seems to work with up to a certain amount of videos. On my Raspberry Pi 4 (2BG RAM), it worked for 16 videos and broke (ran out of memory ?) while merging 36 videos (command and ouput below)

  


  ffmpeg -i 1Rbrdn1Xp.mp4 -i G7eYqdFPb.mp4 -i -Xo-6ABm3.mp4 -i 6As9IlqbW.mp4 -i tz9tVKFA-.mp4
-i MS6DHZoJE.mp4 -i CeJYs99-G.mp4 -i Hsv5X48IC.mp4 -i Gm_DtjNU4.mp4 -i PZytbInZL.mp4
-i qsIJuvKO2.mp4 -i c5wxGk_Fx.mp4 -i j4K1qA7ih.mp4 -i AIpVWuhGV.mp4 -i yiLk0snSh.mp4
-i q1zmytaXZ.mp4 -i VRwQvLxaW.mp4 -i 0_3yLrokH.mp4 -i fW28LPQsk.mp4 -i La6WsGeE8.mp4
-i FlroQnCHq.mp4 -i c7SiL_qSU.mp4 -i aaGTUMJXD.mp4 -i hvXYBaCSM.mp4 -i CMDaFrWM4.mp4
-i _YAGDRyQN.mp4 -i RQXyshs_o.mp4 -i 96pKlIZxW.mp4 -i HVOOeCUYG.mp4 -i pJFxq7BTx.mp4
-i VxMJQqbK5.mp4 -i mkgbViPTI.mp4 -i zrjj93b5c.mp4 -i AL9oG1F36.mp4 -i IsUnC0NPb.mp4
-i Qhj2bhab9.mp4 -y -filter_complex concat=n=36:v=1:a=1 -vsync 2 kn-dQSN-v.mp4


  


  ffmpeg version 4.1.6-1~deb10u1+rpt1 Copyright (c) 2000-2020 the FFmpeg developers
  built with gcc 8 (Raspbian 8.3.0-6+rpi1)
(...)
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '1Rbrdn1Xp.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.20.100
  Duration: 00:00:08.08, start: 0.000000, bitrate: 602 kb/s
    Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1280x720 [SAR 1:1 DAR 16:9], 533 kb/s, 57.62 fps, 60 tbr, 15360 tbn, 120 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 22050 Hz, mono, fltp, 64 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
Input #1, mov,mp4,m4a,3gp,3g2,mj2, from 'G7eYqdFPb.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.20.100
  Duration: 00:00:21.00, start: 0.000000, bitrate: 310 kb/s
    Stream #1:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1280x720 [SAR 1:1 DAR 16:9], 229 kb/s, 59.09 fps, 60 tbr, 15360 tbn, 120 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #1:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 22050 Hz, mono, fltp, 72 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
(...)
Stream mapping:
  Stream #0:0 (h264) -> concat:in0:v0
  Stream #0:1 (aac) -> concat:in0:a0
  Stream #1:0 (h264) -> concat:in1:v0
  Stream #1:1 (aac) -> concat:in1:a0
(...)
  concat:out:v0 -> Stream #0:0 (libx264)
  concat:out:a0 -> Stream #0:1 (aac)
Press [q] to stop, [?] for help
[libx264 @ 0x17cb5e0] using SAR=1/1   0kB time=-577014:32:22.77 bitrate=  -0.0kbits/s speed=N/A    
[libx264 @ 0x17cb5e0] using cpu capabilities: ARMv6 NEON
[libx264 @ 0x17cb5e0] profile High, level 3.2
[libx264 @ 0x17cb5e0] 264 - core 155 r2917 0a84d98 - H.264/MPEG-4 AVC codec - Copyleft 2003-2018 - http://www.videolan.org/x264.html - options: cabac=1 ref=3 deblock=1:0:0 analyse=0x3:0x113 me=hex subme=7 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=6 lookahead_threads=1 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=2 keyint=250 keyint_min=25 scenecut=40 intra_refresh=0 rc_lookahead=40 rc=crf mbtree=1 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
(...)
Output #0, mp4, to 'kn-dQSN-v.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.20.100
    Stream #0:0: Video: h264 (libx264) (avc1 / 0x31637661), yuv420p(progressive), 1280x720 [SAR 1:1 DAR 16:9], q=-1--1, 60 fps, 15360 tbn, 60 tbc (default)
    Metadata:
      encoder         : Lavc58.35.100 libx264
    Side data:
      cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: -1
    Stream #0:1: Audio: aac (LC) (mp4a / 0x6134706D), 22050 Hz, mono, fltp, 69 kb/s (default)
    Metadata:
      encoder         : Lavc58.35.100 aac
frame=15952 fps= 52 q=31.0 size=   10240kB time=00:04:33.02 bitrate= 307.3kbits/s speed=0.844x
[h264 @ 0x3472d80] get_buffer() failed40kB time=00:04:33.02 bitrate= 307.3kbits/s speed=0.844x    
[h264 @ 0x3472d80] thread_get_buffer() failed
[h264 @ 0x3472d80] decode_slice_header error
[h264 @ 0x3472d80] no frame!
Error while decoding stream #15:0: Invalid data found when processing input
[h264 @ 0x34f54d0] get_buffer() failed
[h264 @ 0x34f54d0] thread_get_buffer() failed
[h264 @ 0x34f54d0] decode_slice_header error
[h264 @ 0x34f54d0] no frame!
[h264 @ 0x3472d80] get_buffer() failed
[h264 @ 0x3472d80] thread_get_buffer() failed
(...)
Error while decoding stream #15:0: Invalid data found when processing input
[h264 @ 0x3472d80] reference picture missing during reorder
[h264 @ 0x3472d80] Missing reference picture, default is 65660
[h264 @ 0x34c4540] mmco: unref short failure
[h264 @ 0x34f54d0] get_buffer() failed08kB time=00:04:45.37 bitrate= 316.0kbits/s speed=0.845x    
[h264 @ 0x34f54d0] thread_get_buffer() failed
[h264 @ 0x34f54d0] decode_slice_header error
[h264 @ 0x34f54d0] no frame!
[h264 @ 0x3472d80] decode_slice_header error
[h264 @ 0x3472d80] no frame!
Error while decoding stream #15:0: Invalid data found when processing input
[h264 @ 0x34f54d0] mmco: unref short failure
Error while decoding stream #15:0: Invalid data found when processing input
[h264 @ 0x3472d80] get_buffer() failed
[h264 @ 0x3472d80] thread_get_buffer() failed
[h264 @ 0x3472d80] decode_slice_header error
[h264 @ 0x3472d80] no frame!
Error while decoding stream #15:0: Invalid data found when processing input
[h264 @ 0x3472d80] get_buffer() failed
[h264 @ 0x3472d80] thread_get_buffer() failed
[h264 @ 0x3472d80] decode_slice_header error
[h264 @ 0x3472d80] no frame!
[h264 @ 0x34f54d0] reference picture missing during reorder
    Last message repeated 1 times
[h264 @ 0x34f54d0] Missing reference picture, default is 65708
    Last message repeated 1 times
Error while decoding stream #15:0: Invalid data found when processing input
[h264 @ 0x34dccb0] reference picture missing during reorder
[h264 @ 0x34dccb0] Missing reference picture, default is 65716
[h264 @ 0x3472d80] mmco: unref short failure
[h264 @ 0x34f54d0] decode_slice_header error
[h264 @ 0x34f54d0] no frame!
Error while decoding stream #15:0: Invalid data found when processing inputbits/s speed=0.845x    
[h264 @ 0x3480010] get_buffer() failed
[h264 @ 0x3480010] thread_get_buffer() failed
[h264 @ 0x3480010] decode_slice_header error
[h264 @ 0x3480010] no frame!
[h264 @ 0x34c4540] decode_slice_header error
[h264 @ 0x34c4540] no frame!
Error while decoding stream #15:0: Invalid data found when processing input
[h264 @ 0x3480010] mmco: unref short failure
Error while decoding stream #15:0: Invalid data found when processing input
[h264 @ 0x34c4540] get_buffer() failed
[h264 @ 0x34c4540] thread_get_buffer() failed
[h264 @ 0x34c4540] decode_slice_header error
[h264 @ 0x34c4540] no frame!
Error while decoding stream #15:0: Invalid data found when processing input
[h264 @ 0x34c4540] get_buffer() failed
[h264 @ 0x34c4540] thread_get_buffer() failed
[h264 @ 0x34c4540] decode_slice_header error
[h264 @ 0x34c4540] no frame!
[h264 @ 0x34f54d0] decode_slice_header error
[h264 @ 0x34f54d0] no frame!
Error while decoding stream #15:0: Invalid data found when processing input
[h264 @ 0x3480010] reference picture missing during reorder
    Last message repeated 1 times
[h264 @ 0x3480010] Missing reference picture, default is 65772
    Last message repeated 1 times
Error while decoding stream #15:0: Invalid data found when processing input
[h264 @ 0x3472d80] reference picture missing during reorder
[h264 @ 0x3472d80] Missing reference picture, default is 65780
[h264 @ 0x34c4540] mmco: unref short failure
av_interleaved_write_frame(): Cannot allocate memory
[mp4 @ 0x295c7e0] Application provided duration: 3689347710924763697 / timestamp: 6291454 is out of range for mov/mp4 format
Segmentation fault


  


  Merging videos 2 by 2

  


  I then tried gradually merging videos into one, using multiple FFmpeg commands.

  


  # Pseudocode
final = merge(clip1, clip2)
final = merge(final, clip3)
final = merge(final, clip4)
final = merge(final, clip5)
...


  


  with each command, looking like this :

  


  ffmpeg -i 1Rbrdn1Xp.mp4 -i G7eYqdFPb.mp4 -y -filter_complex concat=n=2:v=1:a=1 -vsync 2 UMVDl9jki.mp4


  


  ffmpeg -i UMVDl9jki.mp4 -i -Xo-6ABm3.mp4 -y -filter_complex concat=n=2:v=1:a=1 -vsync 2 azE1Uombp.mp4


  


  This works but there is a loss in audio quality on the first clips, and it is slowly improving over time. I am guessing this is due to the first videos being merged more times than the last ones. You can see this effect happen in this video (weird artefacts in the voice).

  


  ---

  


  So, am I doing something wrong ?
  
Is there a way of merging a lot of videos, without running out of memory or worsening the audio quality ?