I decided to add support for Sonic Jam’s audio format to FFmpeg, but I didn’t expect it to only take six lines of code! https://awoo.space/media/N9DozT-0zKKE8gz2o6k
* I'm not entirely sure what the video codec is, but it appears to be a macroblock-based format that uses 8x8 macroblocks. This is very unusual for the hardware. It may be MPEG-1 meant to be used with a software decoder, or a very similar custom codec.
* The resolution is 320x144, encoding an image meant to be read at 16:9 using non-square pixels.
Why am I even doing this? Partly, I just want to understand the mystery, lol. And partly because I want to translate the Saturn version of Grandia, which may require me to understand the FMV format.
Well, I gave it a try yesterday, and I guess the "Apple Grandia Data" bitstream is different enough from standard MPEG-1 that FFmpeg doesn't understand it. I wonder if it's actually MPEG-1 or if it's something else.
Also, spent some time today investigating Grandia's extremely weird video format. I think I actually made some progress, so if I'm lucky I'll be able to add full decode support to FFmpeg. What I know so far:
* The container is Quicktime, and mostly standard.
* The stsd atom reports the codec as `cvid` (Cinepak), but this is not correct.
* The audio track is not detected by FFmpeg, but is compressed using the ADX ADPCM format.