How to programmatically get info about e.g. the streams in a file before decoding it.

[olilarkin]

Hello,

Thanks for the tremendous effort on IAMF.

I am integrating support into my project @SpatialAudioKit . I would like to be able to probe an iamf or mp4 file with iamf stream before decoding it, in order to set up audio routings. It's not immediately obvious how i can do this. Can you provide any pointers?

thanks

oli

[yilun-zhangs]

Hi @olilarkin
Unfortunately, even there is one interface IAMF_decoder_get_stream_info() already, but it could not provide more detail information.

We will consider to expand IAMF_StreamInfo{} to include elements numbers, element type, channels, layout, ambisonics orders, etc..

[yilun-zhangs]

Hi @olilarkin

I have checked that ffmpeg supports to probe basic information
I am not sure if ffmpeg could satisfy your requirement before libiamf support it.

Thanks.

[olilarkin]

Thanks, i am aware of ffprobe/libavformat, unfortunately the license is probably too prohibitive. It would be great to get that functionality in libaimf!

Whilst i have your attention i wondered if AOMediaCodec/iamf-tools@c6521c7 indicates that another IAMF decoder will be open sourced?

[yilun-zhangs]

Hi @jwcullen
The decoder mentioned in that commit will be open sourced? I think the decoder is used to generated rendered reference file for each TC in tests directory, right?

Hi @olilarkin
Regarding the probe function, we will continue to consider it.
Thanks.

[jwcullen]

So the encoder in iamf-tools needed a lot of decoder components in order to measure loudness and produce the test rendered wav files. Some things were closed source, but it made sense to open-source it and provide an API around it (currently WIP). It should be treated as an alternative implementation, not the reference decoder.

@olilarkin What type of stuff would you specifically want to probe?

[olilarkin]

I want to be able to visualize the spatial signal in an iamf file, using my engine @SpatialAudioKit, so i need to know how to configure the routing and hook e.g. the ambisonic stream if it exists.