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• Simply beyond ridiculous

  7 mai 2010, par Dark Shikari — H.265, speed

  For the past few years, various improvements on H.264 have been periodically proposed, ranging from larger transforms to better intra prediction. These finally came together in the JCT-VC meeting this past April, where over two dozen proposals were made for a next-generation video coding standard. Of course, all of these were in very rough-draft form ; it will likely take years to filter it down into a usable standard. In the process, they’ll pick the most useful features (hopefully) from each proposal and combine them into something a bit more sane. But, of course, it all has to start somewhere.

  A number of features were common : larger block sizes, larger transform sizes, fancier interpolation filters, improved intra prediction schemes, improved motion vector prediction, increased internal bit depth, new entropy coding schemes, and so forth. A lot of these are potentially quite promising and resolve a lot of complaints I’ve had about H.264, so I decided to try out the proposal that appeared the most interesting : the Samsung+BBC proposal (A124), which claims compression improvements of around 40%.

  The proposal combines a bouillabaisse of new features, ranging from a 12-tap interpolation filter to 12thpel motion compensation and transforms as large as 64×64. Overall, I would say it’s a good proposal and I don’t doubt their results given the sheer volume of useful features they’ve dumped into it. I was a bit worried about complexity, however, as 12-tap interpolation filters don’t exactly scream “fast”.

  I prepared myself for the slowness of an unoptimized encoder implementation, compiled their tool, and started a test encode with their recommended settings.

  I waited. The first frame, an I-frame, completed.

  I took a nap.

  I waited. The second frame, a P-frame, was done.

  I played a game of Settlers.

  I waited. The third frame, a B-frame, was done.

  I worked on a term paper.

  I waited. The fourth frame, a B-frame, was done.

  After a full 6 hours, 8 frames had encoded. Yes, at this rate, it would take a full two weeks to encode 10 seconds of HD video. On a Core i7. This is not merely slow ; this is over 1000 times slower than x264 on “placebo” mode. This is so slow that it is not merely impractical ; it is impossible to even test. This encoder is apparently designed for some sort of hypothetical future computer from space. And word from other developers is that the Intel proposal is even slower.

  This has led me to suspect that there is a great deal of cheating going on in the H.265 proposals. The goal of the proposals, of course, is to pick the best feature set for the next generation video compression standard. But there is an extra motivation : organizations whose features get accepted get patents on the resulting standard, and thus income. With such large sums of money in the picture, dishonesty becomes all the more profitable.

  There is a set of rules, of course, to limit how the proposals can optimize their encoders. If different encoders use different optimization techniques, the results will no longer be comparable — remember, they are trying to compare compression features, not methods of optimizing encoder-side decisions. Thus all encoders are required to use a constant quantizer, specified frame types, and so forth. But there are no limits on how slow an encoder can be or what algorithms it can use.

  It would be one thing if the proposed encoder was a mere 10 times slower than the current reference ; that would be reasonable, given the low level of optimization and higher complexity of the new standard. But this is beyond ridiculous. With the prize given to whoever can eke out the most PSNR at a given quantizer at the lowest bitrate (with no limits on speed), we’re just going to get an arms race of slow encoders, with every company trying to use the most ridiculous optimizations possible, even if they involve encoding the frame 100,000 times over to choose the optimal parameters. And the end result will be as I encountered here : encoders so slow that they are simply impossible to even test.

  Such an arms race certainly does little good in optimizing for reality where we don’t have 30 years to encode an HD movie : a feature that gives great compression improvements is useless if it’s impossible to optimize for in a reasonable amount of time. Certainly once the standard is finalized practical encoders will be written — but it makes no sense to optimize the standard for a use-case that doesn’t exist. And even attempting to “optimize” anything is difficult when encoding a few seconds of video takes weeks.

  Update : The people involved have contacted me and insist that there was in fact no cheating going on. This is probably correct ; the problem appears to be that the rules that were set out were simply not strict enough, making many changes that I would intuitively consider “cheating” to be perfectly allowed, and thus everyone can do it.

  I would like to apologize if I implied that the results weren’t valid ; they are — the Samsung-BBC proposal is definitely one of the best, which is why I picked it to test with. It’s just that I think any situation in which it’s impossible to test your own software is unreasonable, and thus the entire situation is an inherently broken one, given the lax rules, slow baseline encoder, and no restrictions on compute time.

• Batch file runs on one folder and not the next [closed]

  9 novembre 2020, par user1738673

  Who Closed this question before it was resolved ?!? How can I get it reopened ?

  


  After all of the suggestions, here is the code to run in the folder of flac files :

  


  cd /D "%~dp0."

FOR %%# IN ("*.flac") DO (Title %~nx0 Processing: %%~nx#
                ffmpeg -i "%%~nx#" -ab 192k -map_metadata 0 -id3v2_version 3 "%%~n#.mp3")
                    
ECHO Completed %~nx0
PAUSE


  


  Here are my current troubleshooting steps as completed :

  


  I renamed the files in one of the folders in which it does not run to "a.flac", "b.flac", "c.flac", etc. That is to make sure it is not a filename related problem. It did not run.

  


  I renamed the folder itself to a single letter to make sure it was not a folder name issue (F :\MUSIC\j). It did not run.

  


  I copied the entire folder and gave it a new single-letter name (F :\MUSIC\y). It did not run.

  


  I copied the files to a newly-created single-letter named folder at the same directory level (F :\MUSIC\d). It did not work.

  


  I copied the flac files and bat file from the single-letter folder to a newly created single-letter folder. It did not run.

  


  So, I went back the original folder and RENAMED MY .bat FILE from single folder - flac to 192.bat to 192.bat. It ran perfectly.

  


  I went back and renamed the .bat file in all folders described above. They all ran perfectly.

  


  Next, I renamed my master .bat file to single_folder_flac_to_192.bat. I ran it in the original file folder with all of the original names for folder and files. It ran perfectly.

  


  I then copied it into each of the folder described above. It ran perfectly.

  


  I then went back to my original code and renamed it to 192a.bat. This still did not run in the original folder, but ran perfectly in the others I created.

  


  So, I renamed my original folder from 'F :\MUSIC\Yanni - Live At The Acropolis (1994) [FLAC]toylata`. It did not run.

  


  That is all I have time for before needing to go to work. More at lunch time.

  


  Original Post Starts Here :

  


  I am using Windows 10 Pro on my home PC.

  


  I have a batch file which uses ffmpeg to create mp3 from flac and then delete the flac. It runs perfectly in most folders of music. The code is here :

  


  FOR %%a IN ("*.flac") DO (Title %~0 Processing: %%~na.flac
            ffmpeg -i "%%~na.flac" -ab 192k -map_metadata 0 -id3v2_version 3 "%%~na.mp3"
            if not errorlevel 1 if exist "%%~pna.flac" del /q "%%~pna.flac")
ECHO Completed %~n0
PAUSE
                 


  


  In some folders, when I run the batch, it just blinks and goes away. Yes- there are flac files in the folders.

  


  I have checked the different music folders for their properties (read only, access, etc.) and they look identical. The file names are "normal". It doesn't matter which drive I copy the folder into, the results are the same.

  


  I have run the file as Administrator and get the same result.

  


  What else should I be looking into ?

  


• FFMPEG [mp3float @ 0x7fd42f813200] Header missing

  10 février 2021, par rahi82

  I have a problem with some mp3 files. When transcoding the file with FFMPEG I get the following error :

  


  [mp3float @ 0x7fd42f813200] Header missing
Error while decoding stream #0:0: Invalid data found when processing input


  


  Is this a problem of the file itself, and how it is produced ?
Or is it a problem of FFMPEG ?

  


  Here full decoding message :

  


  ffmpeg version git-2020-07-28-dfd12ee Copyright (c) 2000-2020 the FFmpeg developers
  built with Apple clang version 11.0.0 (clang-1100.0.33.16)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/HEAD-dfd12ee_2 --enable-shared --cc=clang --host-cflags= --host-ldflags= --enable-gpl --enable-libaom --enable-libdav1d --enable-libmp3lame --enable-libopus --enable-libsnappy --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libx265 --enable-libfontconfig --enable-libfreetype --enable-frei0r --enable-libass --enable-demuxer=dash --disable-libjack --disable-indev=jack --enable-opencl --enable-videotoolbox --disable-htmlpages --enable-libfdk-aac --enable-nonfree
  libavutil      56. 57.100 / 56. 57.100
  libavcodec     58. 97.102 / 58. 97.102
  libavformat    58. 49.100 / 58. 49.100
  libavdevice    58. 11.101 / 58. 11.101
  libavfilter     7. 87.100 /  7. 87.100
  libswscale      5.  8.100 /  5.  8.100
  libswresample   3.  8.100 /  3.  8.100
  libpostproc    55.  8.100 / 55.  8.100
[mp3 @ 0x7fd42f808200] Estimating duration from bitrate, this may be inaccurate
Input #0, mp3, from 'Ice Mc - Think About The Way.mp3':
  Metadata:
    title           : Think About The Way
    TBPM            : 133
    artist          : Ice MC
    date            : 1994
    track           : 4/15
    disc            : 0
    album_artist    : ICE MC
  Duration: 00:04:16.39, start: 0.000000, bitrate: 323 kb/s
    Stream #0:0: Audio: mp3, 44100 Hz, stereo, fltp, 320 kb/s
    Stream #0:1: Video: mjpeg (Baseline), yuvj420p(pc, bt470bg/unknown/unknown), 600x592 [SAR 72:72 DAR 75:74], 90k tbr, 90k tbn, 90k tbc (attached pic)
    Metadata:
      comment         : Other
Stream mapping:
  Stream #0:1 -> #0:0 (mjpeg (native) -> wrapped_avframe (native))
  Stream #0:0 -> #0:1 (mp3 (mp3float) -> pcm_s16le (native))
Press [q] to stop, [?] for help
Output #0, null, to 'pipe:':
  Metadata:
    title           : Think About The Way
    TBPM            : 133
    artist          : Ice MC
    date            : 1994
    track           : 4/15
    disc            : 0
    album_artist    : ICE MC
    encoder         : Lavf58.49.100
    Stream #0:0: Video: wrapped_avframe, yuvj420p(progressive), 600x592 [SAR 72:72 DAR 75:74], q=2-31, 200 kb/s, 90k fps, 90k tbn, 90k tbc (attached pic)
    Metadata:
      comment         : Other
      encoder         : Lavc58.97.102 wrapped_avframe
    Stream #0:1: Audio: pcm_s16le, 44100 Hz, stereo, s16, 1411 kb/s
    Metadata:
      encoder         : Lavc58.97.102 pcm_s16le
[mp3float @ 0x7fd42f813200] Header missing
Error while decoding stream #0:0: Invalid data found when processing input
frame=    1 fps=0.0 q=-0.0 Lsize=N/A time=00:04:16.60 bitrate=N/A speed= 725x    
video:1kB audio:44204kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown


  


  What is also noticed is that this mp3 has the cover embedded as a video stream. And there is also this weird cross mapping. Not sure if that is normal ?