On 3/3/22, Paul B Mahol <one...@gmail.com> wrote: > On 2/27/22, Jack Bruienne <jackbruie...@gmail.com> wrote: >> >> From the wiki page (https://wiki.vexatos.com/dfpwm): >>> DFPWM (Dynamic Filter Pulse Width Modulation) is an audio codec >>> created by Ben “GreaseMonkey” Russell in 2012, originally to be used >>> as a voice codec for asiekierka's pixmess, a C remake of 64pixels. >>> It is a 1-bit-per-sample codec which uses a dynamic-strength one-pole >>> low-pass filter as a predictor. Due to the fact that a raw DPFWM >>> decoding >>> creates a high-pitched whine, it is often followed by some >>> post-processing >>> filters to make the stream more listenable. >> >> It has recently gained popularity through the ComputerCraft mod for >> Minecraft, which added support for audio through this codec, as well as >> the Computronics expansion which preceeded the official support. These >> both implement the slightly adjusted 1a version of the codec, which is >> the version I have chosen for this patch. >> >> This patch adds a new codec (with encoding and decoding) for DFPWM1a. >> The codec sources are pretty simple: they use the reference codec with >> a basic wrapper to connect it to the FFmpeg AVCodec system. >> >> To clarify, the codec does not have a specific sample rate - it is >> provided by the container (or user), which is typically 48000, but has >> also been known to be 32768. The codec does not specify channel info >> either, and it's pretty much always used with one mono channel. >> However, since it appears that libavcodec expects both sample rate and >> channel count to be handled by either the codec or container, I have >> made the decision to allow multiple channels interleaved, which as far >> as I know has never been used, but it works fine here nevertheless. The >> accompanying raw format has a channels option to set this. (I expect >> most users of this will not use multiple channels, but it remains an >> option just in case.) >> >> This patch will be highly useful to ComputerCraft developers who are >> working with audio, as it is the standard format for audio, and there >> are few user-friendly encoders out there, and even fewer decoders. It >> will streamline the process for importing and listening to audio, >> replacing the need to write code or use tools that require very >> specific input formats. >> >> You may use the CraftOS-PC program (https://www.craftos-pc.cc) to test >> out DFPWM playback. To use it, run the program and type this command: >> "attach left speaker" Then run "speaker play <file.dfpwm>" for each file. >> The app runs in a sandbox, so files have to be transferred in first; >> the easiest way to do this is to simply drag the file on the window. >> (Or copy files to the folder at https://www.craftos-pc.cc/docs/saves.) >> >> Sample DFPWM files can be generated with an online tool at >> https://music.madefor.cc. This is the current best way to encode DFPWM >> files. Simply drag an audio file onto the page, and it will encode it, >> giving a download link on the page. >> >> I've made sure to update all of the docs as per Developer§7, and I've >> tested it as per section 8. Test files encoded to DFPWM play correctly >> in ComputerCraft, and other files that work in CC are correctly decoded. >> I have also verified that corrupt files do not crash the decoder - this >> should theoretically not be an issue as the result size is constant with >> respect to the input size. >> >> Changes since v4: >> Fixed missing channel check in decoder. >> >> Changes since v3: >> Added support for multiple interleaved channels, and cleaned up the >> code a bunch. >> >> Changes since v2: >> I've found that the reference encoder has a few errors, and sounds >> worse than the Java-based implementation that is used most often. I got >> in contact with someone who knows DFPWM much better than I do, and I >> worked with them to make a few adjustments that should improve the >> audio quality. I also made sure that the output matches the Java >> codec exactly, so it should have the exact same quality as other codecs. >> >> Signed-off-by: Jack Bruienne <jackbruie...@gmail.com> >> --- >> Changelog | 1 + >> MAINTAINERS | 1 + >> doc/general_contents.texi | 1 + >> libavcodec/Makefile | 2 + >> libavcodec/allcodecs.c | 2 + >> libavcodec/codec_desc.c | 7 ++ >> libavcodec/codec_id.h | 1 + >> libavcodec/dfpwmdec.c | 133 ++++++++++++++++++++++++++++++++++++++ >> libavcodec/dfpwmenc.c | 121 ++++++++++++++++++++++++++++++++++ >> libavcodec/utils.c | 2 + >> libavcodec/version.h | 2 +- >> 11 files changed, 272 insertions(+), 1 deletion(-) >> create mode 100644 libavcodec/dfpwmdec.c >> create mode 100644 libavcodec/dfpwmenc.c >> >> > > > Please move channel check to init. >
Also check for possible overflows when multiplying with 8 the packet->size. _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
