Hi, On Thu, May 22, 2025 at 1:59 PM Ronald S. Bultje <rsbul...@gmail.com> wrote: > On Wed, May 21, 2025 at 9:34 AM Timothée < > timothee.informati...@regaud-chapuy.fr> wrote: > > I am interested in expanding ffmpeg's capabilities to extract > > low-level data from video codecs. Specifically, I'd like to implement > > functionality that would allow exporting frame data, macroblock > > information, quantization tables, and similar codec-specific elements > > to binary files for further analysis. > > > > After searching through the documentation and existing features, I > > haven't found similar functionality, though I may have missed > > something. Has this been implemented before, or are there related > > features I should examine? > > Some older codecs implement minor variants for this, e.g. grep > for AV_FRAME_DATA_MOTION_VECTORS, which attaches a frame's motion vectors > to the picture data. I believe there's an example app and possibly a filter > to overlay MVs on top of the video frame based on this concept. You could > extend this to cover other (macro)block info. There used to be a variant of > this for quant-tables also but I can't find it, maybe it was removed.
If I recall correctly, we wanted to move away from exporting more of this kind of codec-specific information as picture data. Timothée, this kind of feature depends a lot on the codec that you want to work with. It will also depend on which syntax elements you need from the codec. In FFmpeg, there is the CBS code which describes the bitstream for a few codecs, which might help you. I have a separate project (called FFglitch), which lets you export some elements (such as quantization tables, dct coefficients, and motion vectors) from some codecs (jpeg, mpeg2, mpeg4) to JSON format, and even modify them in the bitstream. In the end, it will depend on what you want to do with the extracted low-level data, and for which codecs. Ramiro _______________________________________________ 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".
