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• How to concatenate .mp4 files into one 4x4 movie using -ffmpeg- ?

  7 août 2021, par Clive Nicholas

  How should I best concatenate 16 separate .mp4 files into one 4x4 movie using -ffmpeg- ?

  


  I have workable code to create 2x2 movies (with changeable optional flag calls), with four equally-sized files, thus :

  


  ffmpeg -i foo1.mp4 -i foo2.mp4 -i foo3.mp4 -i foo4.mp4 \ 
 -filter_complex \
   "[0:v][1:v]hstack[t]; \
    [2:v][3:v]hstack[b]; \
    [t][b]vstack,format=yuv420p[v]; \
    [0:a][1:a][2:a][3:a]amerge=inputs=4[a]" \
-map "[v]" \ 
-map "[a]" \
-ac 2 -c:v libx264 \
foo.mp4


  


  and with four unequally-sized files, thus :

  


  ffmpeg -i foo1.mp4 -i foo2.mp4 -i foo3.mp4 -i foo4.mp4 \
 -filter_complex \
   "[0:v]scale=640:360[v0]; \
    [1:v]scale=640:360[v1]; \
    [2:v]scale=640:360[v2]; \
    [3:v]scale=640:360[v3]; \
    [v0][v1]hstack[t]; \
    [v2][v3]hstack[b]; \
    [t][b]vstack,format=yuv420p[v]; \
    [0:a][1:a][2:a][3:a]amerge=inputs=4[a]" \
-map "[v]" \
-map "[a]" \
-c:v libx264 -crf 23 \
-c:a aac -b:a 192k \
foo.mp4


  


  There is a solution posted here for splitting a single movie file into 16 4x4 pieces, but naturally I want to do the opposite ! I can't quite work out in my own mind how I can knit together the necessary elements from my 2x2 code routines and the 4x4 split code into a satisfactory 4x4 solution. It may well be that the 16 individual movie files each have to be re-scaled downwards.

  


  Any ideas would be gratefully received, especially coding solutions which are readily tweakable to any matrix combination (e.g., 3x3, 5x5, etc).

  


  Thanks very much, Clive

  


• MPEG-4 and alpha transparency - the ongoing saga

  16 janvier 2016, par OrangeDog

  I’d like to reach some sort of definitive answer for the following questions :

  1. Is alpha transparency supported in MPEG-4-based codecs ?
  2. Is there any way to be reasonably certain that there is no alpha-channel from the output of ffprobe ?

  Some links I’ve found on the subject :

  • http://stackoverflow.com/a/5057631/476716

  Also, transparent alpha layers, an optional part of the H.264 specification, are now supported in H.264-based QuickTime movies.

  • http://software.intel.com/en-us/articles/alpha-channel-support-in-the-h264-decoder-in-ipp/

  The support for alpha channel in the H.264 decoder is now available in Intel® Integrated Performance Primitives 6.0 version.

  • http://forums.creativecow.net/readpost/335/30475

  The MPEG4 Simple Studio Profile supports auxiliary channels, which could be used for alpha or depth — and presumably even displacement, motion vectors, normals, etc.

  However, I’ve never seen a concrete example, or indeed any details on how you use these announced features.

• How fix FFMPEG No decoder surfaces left error [closed]

  14 juillet 2021, par R.A.M

  
Anybody know how could i fix this problem ?
  


  [h264 @ 0x56086cab3340] No decoder surfaces left
Error while decoding stream #0:0: Invalid data found when processing input0
Impossible to convert between the formats supported by the filter 
'Parsed_scale_npp_0' 
and the filter 'auto_scaler_0'
Error reinitializing filters!
Failed to inject frame into filter network: Function not implemented
Error while processing the decoded data for stream #0:0
[aac @ 0x56086bd86fc0] Qavg: 680.716
[aac @ 0x56086bd86fc0] 2 frames left in the queue on closing
[aac @ 0x56086bd88c40] Qavg: 680.716
[aac @ 0x56086bd88c40] 2 frames left in the queue on closing


  


  Let me explain more about my problem :
  
When i transcoding a video on GPU use CUDA, get this error on some movies (not all my video)
  
It works currectly on many videos but has exception in some video like this.
  
When i use Cpu for transcoding this type of video(that has problem) it works and not have any exception and errors.
  
In fact i think problem is on CUDA.
  
The FFMPEG command that i use, is :
  

  


  ffmpeg -y -loglevel info -hwaccel cuda -hwaccel_output_format cuda -hwaccel_device 0 
-i MY_VIDEO.mp4 -vf scale_npp=w=1280:h=720 -c:v h264_nvenc -profile:v main -b:v 
1500000 -sc_threshold 0 -g 25 -keyint_min 25 -bf 2 -c:a aac -b:a 128000 -ar 48000 - 
hls_segment_filename f-4-seg-%d.ts f-4.m3u8


  


  Thanks