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• Patent skullduggery : Tandberg rips off x264 algorithm

  25 novembre 2010, par Dark Shikari — patents, ripoffs, x264

  Update : Tandberg claims they came up with the algorithm independently : to be fair, I can actually believe this to some extent, as I think the algorithm is way too obvious to be patented. Of course, they also claim that the algorithm isn’t actually identical, since they don’t want to lose their patent application.

  I still don’t trust them, but it’s possible it’s merely bad research (and thus being unaware of prior art) as opposed to anything malicious. Furthermore, word from within their office suggests they’re quite possibly being honest : supposedly the development team does not read x264 code at all. So this might just all be very bad luck.

  Regardless, the patent is still complete tripe, and should never have been filed.
  

  Most importantly, stop harassing the guy whose name is on the patent (Lars) : he’s just a programmer, not the management or lawyers responsible for filing the patent. This is stupid and unnecessary. I’ve removed the original post because of this ; it can be found here for those who want to read it.

  Appendix : the details of the patent :

  I figure I’ll go over the exact correspondence between the patent and my code here.

  1. A method for calculating run and level representations of quantized transform coefficients representing pixel values included in a block of a video picture, the method comprising :

  Translation : It’s a run-level coder.

  packing, at a video processing apparatus, each quantized transform coefficients in a value interval [Max, Min] by setting all quantized transform coefficients greater than Max equal to Max, and all quantized transform coefficients less than Min equal to Min

  The quantized coefficients are clipped to a certain valid range to allow them to be packed into bytes (they start as 16-bit values).

  reordering, at the video processing apparatus, the quantized transform ID coefficients according to a predefined order depending on respective positions in the block resulting in an array C of reordered quantized transform coefficients

  This is the zigzag pattern used in H.264 (and most formats) for reordering DCT coefficients. In x264, this is done before the run-level coder ste.

  masking, at the video processing apparatus, C by generating an array M containing ones in positions corresponding to positions of C having non-zero values, and zeros in positions corresponding to positions of C having zero values

  This is creating a bitmask based on the coefficient values, the pmovmskb step.

  is generating, at the video processing apparatus, for each position containing a one in M, a run and a level representation by setting the level value equal to an occurring value in a corresponding position of C ; and setting, at the video processing apparatus, for each position containing a one in M₅ the run value equal to the number of proceeding positions relative to a current position in M since a previous occurrence of one in M.

  This is the process of creating run/level values from the bitmask.

  Now into the detailed claims :

  2. The method according to Claim 1, wherein the masking further includes, creating an array C from C where positions corresponding to positions of nonzero values in C are filled with ones, and positions corresponding to positions of zero values in C are filled with zeros, and creating M from C by extracting the most significant bit from values in respective position of C and inserting the bits in corresponding positions in M.

  They’re extracting the most significant bit of the values to create a bitmask. This is exactly what the pmovmskb in my algorithm does.

  3. The method according to Claim 2, wherein the creating of the array C is executed by a C++ function PCMPGTB, and the creating of M from C is executed by a C++ function PMOVMSKB.

  And here they use pcmpgtb (they call it a C++ function for some reason, but it’s a SSE instruction) to do the clipping of the input values. This is exactly the same method I used in decimate_score. They also use pmovmskb as mentioned.

  4. The method according to Claim 1 , wherein the generating of the run and level representation further includes determining positions containing non-zero values in C by corresponding positions containing ones in M.

  5. The method according to Claim 4, wherein the determining of positions containing non-zero values in C is executed by a C++ function BSF.

  Here they iterate over the bitmask of transform coefficients using a “BSF” function to find runs, which is exactly what I did. Of course, BSF isn’t a function, it’s an x86 instruction.

  6. The method according to Claim 1 , wherein Max is 256 and Min is 0.

  This is almost surely a typo or mistake of some sort. They mean the Max should be 255, not 256 : 256 doesn’t fit in a uint8_t.

  7. The method according to Claim 1 , wherein the predefined order follows a zigzag path of transform coefficient positions in the block starting in an upper left corner heading towards a lower right corner.

  This is a description of the typical DCT zigzag pattern (like in H.264, MPEG-2, Theora, etc).

  Everything after this part is just repeating itself with the phrase “an apparatus” added in order to make the USPTO listen to them.

• Adding album cover art to FLAC audio files using `ffmpeg`

  27 décembre 2022, par user5395338

  I have ripped files from an audio CD I just bought. I ripped using the Music app on my Macbook Pro, Catalina 10.15.6 - output format was .wav as there was no option for FLAC. My plan was to change format using ffmpeg :

  


  % ffmpeg -v
ffmpeg version 4.4 Copyright (c) 2000-2021 the FFmpeg developers


  


  Except for the "album cover artwork" addition, the .wav-to-.flac conversion implemented in the short bash script below seems to have worked as expected :

  


  #!/bin/bash
for file in *.wav
do
echo $file 
ffmpeg -loglevel quiet -i "$file" -ar 48000 -c:a flac -disposition:v AnotherLand.png -vsync 0 -c:v png "${file/%.wav/.flac}"
done


  


  A script very similar to this one worked some time ago on a series of FLAC-to-FLAC conversions I had to do to reduce the bit depth. However, in that case, the original FLAC files already had the artwork embedded. Since this script produced usable audio files, I decided that I would try adding the artwork with a second ffmpeg command.

  


  I did some research, which informed me that there have been issues with ffmpeg (1, 2, 3, 4) on adding album artwork to FLAC files.

  


  I have tried several commands given in the references above, but still have not found a way to add album artwork to my FLAC files. The following command was a highly upvoted answer, which I felt would work, but didn't :

  


  % ffmpeg -i "01 Grave Walker.flac" -i ./AnotherLand.png -map 0:0 -map 1:0 -codec copy -id3v2_version 3 -metadata:s:v title="Album cover" -metadata:s:v comment="Cover (front)" output.flac

...


Input #0, flac, from '01 Grave Walker.flac':
  Metadata:
    encoder         : Lavf58.76.100
  Duration: 00:06:59.93, start: 0.000000, bitrate: 746 kb/s
  Stream #0:0: Audio: flac, 48000 Hz, stereo, s16
Input #1, png_pipe, from './AnotherLand.png':
  Duration: N/A, bitrate: N/A
  Stream #1:0: Video: png, rgba(pc), 522x522, 25 fps, 25 tbr, 25 tbn, 25 tbc
File 'output.flac' already exists. Overwrite? [y/N] y
[flac @ 0x7fb4d701e800] Video stream #1 is not an attached picture. Ignoring
Output #0, flac, to 'output.flac':
  Metadata:
    encoder         : Lavf58.76.100
  Stream #0:0: Audio: flac, 48000 Hz, stereo, s16
  Stream #0:1: Video: png, rgba(pc), 522x522, q=2-31, 25 fps, 25 tbr, 25 tbn, 25 tbc
    Metadata:
      title           : Album cover
      comment         : Cover (front)
Stream mapping:
  Stream #0:0 -> #0:0 (copy)
  Stream #1:0 -> #0:1 (copy)

...



  


  I don't understand the error message : Video stream #1 is not an attached picture. It seems to imply that that the artwork is "attached" (embedded ???) in the input file, but as I've specified the artwork is a separate file, this makes no sense to me.

  


• ffmpeg built on mac 10.13 fails when ran on other computer (dyld : Library not loaded libmp3lame.0.dylib)

  15 mars 2023, par Martin

  I have a shell script called buildffmpeg.sh which I call with the command $ sh buildffmpeg.sh on my mac os high sierra 10.13 machine :

  


  #!/bin/bash

# If you get error `c compiler failed` run `sudo apt install libglfw3-dev libglew-dev`
# apt-get install build-essential
# apt-get build-dep ffmpeg
# when running this on mac, you need to install some libraries such as 'brew install opus'

set -e

CWD=$(pwd)
PACKAGES="$CWD/packages"
WORKSPACE="$CWD/workspace"
ADDITIONAL_CONFIGURE_OPTIONS=""


mkdir -p "$PACKAGES"
mkdir -p "$WORKSPACE"

FFMPEG_TAG="$1"
FFMPEG_URL="http://git.ffmpeg.org/gitweb/ffmpeg.git/snapshot/74c4c539538e36d8df02de2484b045010d292f2c.tar.gz"

FFMPEG_ARCHIVE="$PACKAGES/ffmpeg.tar.gz"

if [ ! -f "$FFMPEG_ARCHIVE" ]; then
    echo "Downloading tag ${FFMPEG_TAG}..."
    curl -L -o "$FFMPEG_ARCHIVE" "$FFMPEG_URL"
fi

EXTRACTED_DIR="$PACKAGES/extracted"

mkdir -p "$EXTRACTED_DIR"

echo "Extracting..."
tar -xf "$FFMPEG_ARCHIVE" --strip-components=1 -C "$EXTRACTED_DIR"

cd "$EXTRACTED_DIR"

echo "Building..."

# Min electron supported version
MACOS_MIN="10.10"

./configure $ADDITIONAL_CONFIGURE_OPTIONS \
    --pkgconfigdir="$WORKSPACE/lib/pkgconfig" \
    --prefix=${WORKSPACE} \
    --pkg-config-flags="--static" \
    --extra-cflags="-I$WORKSPACE/include -mmacosx-version-min=${MACOS_MIN}" \
    --extra-ldflags="-L$WORKSPACE/lib -mmacosx-version-min=${MACOS_MIN} -L/usr/local/opt/lame/lib -Wl,-rpath,/usr/local/opt/lame/lib" \
    --extra-libs="-lpthread -lm" \
    --enable-static \
    --disable-securetransport \
    --disable-debug \
    --disable-shared \
    --disable-ffplay \
    --disable-lzma \
    --disable-doc \
    --enable-version3 \
    --enable-pthreads \
    --enable-runtime-cpudetect \
    --enable-avfilter \
    --enable-filters \
    --disable-libxcb \
    --enable-gpl \
    --disable-libass \
    --enable-libmp3lame \
    --enable-libx264 \
    --enable-libopus

make -j 4
make install

otool -L "$WORKSPACE/bin/ffmpeg"
otool -L "$WORKSPACE/bin/ffprobe"

echo "Building done. The binaries can be found here: $WORKSPACE/bin/ffmpeg $WORKSPACE/bin/ffprobe"

mkdir ffmpeg-mac/ 
cp -r "$WORKSPACE/bin/" "$CWD/ffmpeg-mac/"

rm -rf "$PACKAGES"
rm -rf "$WORKSPACE"

exit 0



  


  When it finishes, I have a folder ffmpeg-mac/ which contains two built executables ffmpeg and ffprobe.

  


  but if I try to move the ffmpeg-mac folder onto my other macbook, running 11.2.3 big sur, and if i try to call my built ffmpeg file with ./ffmpeg-mac/ffmpeg, it fails with this error :

  


  $ ./ffmpeg-mac/ffmpeg 
dyld: Library not loaded: /usr/local/opt/lame/lib/libmp3lame.0.dylib
  Referenced from: /Users/martinbarker/Documents/projects/rendertunev1.1.2/./ffmpeg-mac/ffmpeg
  Reason: image not found
Abort trap: 6



  


  So I think when I run the script to build ffmpeg on my mac 10.13 high sierra machine, it for some reason is not including the file libmp3lame.0.dylib. I've tried using brew to uninstall, install, unlink, and link lame, but no luck. I've tried manually editing my shell script to include the file but no luck.

  


  Can anyone help me fix my build script so that when I build ffmpeg on high sierra, I can use the finished built file on other mac computers ?