Does this use hardware acceleration in WebGL?

[taimooralam]

I need to confirm whether the WebGL optimizations in Broadway use hardware acceleration features to further decrease the latency while decoding H.264 data?

[soliton4]

technically yes but its not hardware accelerated decoding

[mbebenita]

Only a small portion of the decoding path uses hardware acceleration, namely YCbCr to RGB conversion. The main benefit of this is two fold:

1. The colorspace conversion math is non-trivial and it's slow when executed on the CPU.
2. Texture uploads are slow. Uploading YCbCr instead of RGB image data is faster, since you're dealing with half as much data.

[taimooralam]

1. If I have H264 data in my browser and I want to decode and render it with a combined latency of 10-15 ms. Is that possible in your opinion?
2. How can I get data from an RTSP stream in the Webpage, if you have any idea about that?

[soliton4]

i am working on low latency applications as well. it is possible, but you need to know what you are doing on the encoder side base profile and only p-frames http://www.streaminglearningcenter.com/articles/producing-h264-video-for-flash-an-overview.html?page=4

[taimooralam]

Thanks. Can you please tell me which part that converts YUV to RGB?

[soliton4]

the color conversion on a webgl system happens here: https://github.com/mbebenita/Broadway/blob/master/Player/YUVCanvas.js#L279

[amilajack]

Is it theoretically possible to enable hardware acceleration in WebGL or javascript?

[soliton4]

most webgl implementations run on processors outside the cpu. which could also be called hardware accelerated.

[amilajack]

So currently the decoding of mp4 is not hardware accelerated?