Re: [rtcweb] VP8 / H.264 conversion without transcoding

"Mo Zanaty (mzanaty)" <> Thu, 21 November 2013 14:27 UTC

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From: "Mo Zanaty (mzanaty)" <>
To: Bossiel <>
Thread-Topic: [rtcweb] VP8 / H.264 conversion without transcoding
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Date: Thu, 21 Nov 2013 14:27:27 +0000
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Subject: Re: [rtcweb] VP8 / H.264 conversion without transcoding
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This probably refers to an intelligent transcoder versus a brute force transcoder. An intelligent transcoder harvests more data during decoding than just the raw output pixels, and uses this extra data to ease encoding. Data like block partitions, motion vectors, intra modes, quantization parameters, etc.

This is common for common conversions, like MPEG2 to H.264. VP8 and H.264 are much closer formats, so this can significantly improve transcoder performance.

However, this is strictly a performance optimization, with no impact on IPR or licensing issues.


On Nov 21, 2013, at 2:51 AM, "Bossiel" <<>> wrote:

This could be true if they can also walk on water and change it into wine.
To be serious, no it's not possible.

Sent from my iPhone

On Nov 21, 2013, at 3:13, Gili <<>> wrote:


I'm at the WebRTC World conference. If I understood correctly, Zingaya just demoed what they claim is a VP8 to H.264 bridge that converts the video without transcoding. My interpretation is that they convert the surrounding packet format without re-encoding the actual video. Someone who understands codec internals (I don't) might want to validate this claim, because it could have a significant impact on the MTI debate.

It sounds far fetched, but imagine the possibilities:

  1.  If the video is not being re-encoded, do H.264 royalties apply?
  2.  If the conversion is really cheap, is it feasible to connect a H.264 peer to a VP8 peer and have one of them convert in-line (no MCU)?


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