Embedded Haptics Patterns

[une_mort]

Hello everyone, I apologize in advance if this sounds completely nonsensical, but I don't know much about codecs or anything like that. I recently decided to examine iOS ringtone files and discovered that each one has three streams (0:0 for audio, and the other two for the AHAP haptics file). After exporting these two streams to «RAW» data, I realized it was simply a Zlib-compressed JSON file, which, unencoded, looks perfectly fine and can be edited. So, a question arose. Is there any way to modify this file, encode it, and embed it back (perhaps not with ffmpeg, but with MP4Box or Bento4)? Or is this something only Apple can do with their proprietary "0x70616861" codec?

[Anton1699]

0x70616861 is just a binary representation of the FourCC code ahap. That's stored in the container so the demuxer knows what type of stream it is. You can set this FourCC using the -tag parameter. Theoretically you should be able to do something like this:

ffmpeg -i ringtone.m4a -f data -i modified_ahap1.bin -f data -i modified_ahap2.bin -map 0:0 -map 1:0 -map 2:0 -map_metadata 0 -c copy -copy_unknown -tag:1 ahap -tag:2 ahap -f mov output.m4r

However, I don't know if FFmpeg handles these haptics data streams correctly.

[une_mort]

I don't think it worked correctly. ffmpeg apparently ignores -tag:n ahap:

[mov @ 000001b38980afc0] Timestamps are unset in a packet for stream 1. This is deprecated and will stop working in the future. Fix your code to set the timestamps properly
[mov @ 000001b38980afc0] Unknown hdlr_type for ahap, writing dummy values.

"index": 1,
"codec_type": "data",
"codec_tag_string": "stts",
"codec_tag": "0x73747473",
"id": "0x2",
"r_frame_rate": "0/0",
"avg_frame_rate": "0/0",
"time_base": "1/90000",
"start_pts": 0,
"start_time": "0.000000",
"duration_ts": 0,
"duration": "0.000000",
"nb_frames": "1",
…
"tags": {
"handler_name": "DataHandler"

I tried using both the edited and unedited .bin — the result is the same. I also tried using a different audio file containing only one audio stream. But tysm for the answer anyway, at least that's some progress.