Thread: The limits of Redcode/Redray

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  1. #1 The limits of Redcode/Redray 
    Hi,
    I bought the Redray to encode my own computer generated 4K material. I hoped it would work as with 'normal' material from digital cameras or film scans.
    It seems I was too optimistic. I realise Redray is amazing for what it is compared to the current state of h265 or other codecs. But it can't do wonders.
    My material has even at 36 Mbit/s visible compression artifacts. I could live with that as the artifacts are not very strong and h265 at this rate is unwatchable.
    What I can not live with is the fact that my material is not compatible with the real time decoding capabilities of Redray, it seems. The player can't keep up.
    There is stuttering, blackouts, distorted sound and other anomalies coming and going with image complexity. I tried playback on a Dell 4K monitor and a
    new JVC 'pseudo' 4K projector. On the monitor only the stuttering is visible. On the projector there are also the blackouts etc.
    Does anyone else have similar experiences? Any solutions possible in addition to 'dumbing down' the source (e.g. remove detail).
    Michel Hafner
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  2. #2  
    Moderator Phil Holland's Avatar
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    The only blackouts I've had was solved by purchasing better quality "high speed" HDMI cables. This also effected the audio.

    I haven't had any stuttering during playback however. That's a new one for me.

    I'd be curious to hear more about the artifacts your experiencing at 36Mbps.
    Phil Holland - Cinematographer - Los Angeles
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  3. #3  
    Quote Originally Posted by Phil Holland View Post

    I'd be curious to hear more about the artifacts your experiencing at 36Mbps.
    Clean smooth gradients next to high detail areas show compression noise. The high detail areas are 'chaotic' enough to mask any compression noise, The smooth gradients show issues without mercy.
    Michel Hafner
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  4. #4  
    Moderator Phil Holland's Avatar
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    Quote Originally Posted by Michel Hafner View Post
    Clean smooth gradients next to high detail areas show compression noise. The high detail areas are 'chaotic' enough to mask any compression noise, The smooth gradients show issues without mercy.
    Just out of curiosity is your source material 16 bit?
    Phil Holland - Cinematographer - Los Angeles
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    phfx.com IMDB
    PHFX | tools

    2X RED Monstro 8K VV Bodies and a lot of things to use with them.

    Data Sheets and Notes:
    Red Weapon/DSMC2
    Red Dragon
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  5. #5  
    Quote Originally Posted by Phil Holland View Post
    Just out of curiosity is your source material 16 bit?
    8 bit. But the noise is not there in the uncompressed version. Anyway, the issue is the stuttering. The noise I can live with,
    Michel Hafner
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  6. #6  
    All the preloaded clips and new examples show size 4096 * 2304. How exactly does Redray output to a UHD device? Scaling real time to 3840 * 2160? Cropping real time to 3840 * 2160? Leaving it to the device to scale/crop? Could the decoding plus reformatting exceed the processing limit? I think when I set central crop to UHD size for encoding my 4K files there are less problems during playback. Does that make sense?
    Michel Hafner
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  7. #7  
    Quote Originally Posted by Michel Hafner View Post
    Clean smooth gradients next to high detail areas show compression noise. The high detail areas are 'chaotic' enough to mask any compression noise, The smooth gradients show issues without mercy.
    Any chance you can show some samples? Even provide an uncompressed frame or two that we can see if it's an issue to duplicate? I've been trying to break the compression and while it's not perfect, it's pretty darn close and I haven't run into any issues like you're describing.

    Have you contacted RED?
    - Jeff Kilgroe
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    - Just me and my 8K Monstro VV kicking ass.
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  8. #8  
    I'll contact Red about this. The stuttering only happens when encoding with no crop. When cropping to UHD glitches can happen but are far more rare.
    So does anyone know: How exactly does Redray output to a UHD device? Scaling real time to 3840 * 2160? Cropping real time to 3840 * 2160? Leaving it to the device to scale/crop?
    ??
    Michel Hafner
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  9. #9  
    Moderator Phil Holland's Avatar
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    I've been mastering everything at 4096x2160 at the moment and placing my 16x9 within that container, which provides the correct aspect ratio and content on UHD displays as far as I can tell. If you notice and export 3840x2160 you are losing some of the side content as it's "fitting to width" to the 4096 dimension. At least that's been my experience on most displays.

    As for the source content. I would really need to see what the 8 bit stuff is. That is likely the culprit when it comes to gradient related details. Also I need to know more about the source imagery.

    The best quality results I've been able to achieve are rather similar to how you would get the best results mastering a DCP. 16 bit source image sequences are useful as you are giving the encoder more of a "choice". Whereas 8 bit to REDRAY 12 bit might be a little less. That's my theory at least.
    Phil Holland - Cinematographer - Los Angeles
    ________________________________
    phfx.com IMDB
    PHFX | tools

    2X RED Monstro 8K VV Bodies and a lot of things to use with them.

    Data Sheets and Notes:
    Red Weapon/DSMC2
    Red Dragon
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  10. #10  
    Update: Red has got test samples that show the problem. They see the problem too. They are looking into it. So far no feedback what's causing it.
    Michel Hafner
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