allow to copy latm aac to raw aac without reencoding audio

[Nuno]

I would like to purpose an enhancement to ffmpeg, so that it would be possible to copy latm aac stream to raw aac without reencoding audio, possibly through a bitstream filter (similar to the existing aac_adtstoasc), it would allow to do something like:

ffmpeg -i in.ts -vcodec copy -acodec copy -absf aac_latmtoraw out.mkv

ffmpeg already includes code to handle latm aac (then it may be an easy task?), for eg. this will work on the same source file with latm aac:

ffmpeg -i in.ts -vcodec copy -acodec libvo_aacenc out.mkv

but doing this will obviously reencode aac audio and what I'm suggesting is a way to convert it from latm to raw aac without the need to reencode audio.

P.S. This feature would be useful to convert ts files recorded from some DVB-T streams to mkv, doing copy of latm stream to mkv doesn't seem to be well supported on many players while raw aac is.

[Adam M. Costello]

I wish I could do the reverse: copy aac to aac_latm without recoding. Why? Because my TiVo can pull H.264 video and AAC audio from my PC, but only when they're wrapped in mpegts and latm. My camera produces them as an mp4. The conversion could in principle be done with no recoding, but currently with ffmpeg I have no choice but to recode the audio (to ac3 for example), because ffmpeg cannot produce latm.