The problem with HDR is that it requires 10 bit color depth to look decent. (OBS does not even allow it with 8 bit even though technically it's possible)
h264 supports 10 bit but hardware support is not wide spread. NVidia GPUs for example have no support for 10 bit h264 for decode or encode.
YouTube supports HDR streaming using h265 but they reencode the stream to vp9 on the fly. 1. because they always do that for different resolutions and 2. to avoid the patent issues with that codec. This is not an option for twitch since they don't do reencode for normal people.
Direct vp9 support could be an option. But there is no hardware encoder support as far as i know. But the decoder support is great. This could be an option for all of those with dedicated streaming pc's that can handle heavy CPU encode.
The solution would probably be av1 support. Here we already have some great hardware encoders but decode support on smart tv's and older smartphones will be an issue (software decode is an option)
The other issue is that twitch does not do reencode server side. So the client will have to map HDR to SDR if needed.
The problem with HDR is that it requires 10 bit color depth to look decent. (OBS does not even allow it with 8 bit even though technically it's possible)
h264 supports 10 bit but hardware support is not wide spread. NVidia GPUs for example have no support for 10 bit h264 for decode or encode.
YouTube supports HDR streaming using h265 but they reencode the stream to vp9 on the fly. 1. because they always do that for different resolutions and 2. to avoid the patent issues with that codec. This is not an option for twitch since they don't do reencode for normal people.
Direct vp9 support could be an option. But there is no hardware encoder support as far as i know. But the decoder support is great. This could be an option for all of those with dedicated streaming pc's that can handle heavy CPU encode.
The solution would probably be av1 support. Here we already have some great hardware encoders but decode support on smart tv's and older smartphones will be an issue (software decode is an option)
The other issue is that twitch does not do reencode server side. So the client will have to map HDR to SDR if needed.