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  1. When I record a show on the PVR using the HD6400 Bell receiver I would think it's hardware encoded H.264 with some predetermined bitrate. A 2Tb drive allows me to record about 500 hours of HD programming. Converting that into a bitrate that works out to 8.88 Mb/sec.

    So if I record from the recorded show, Wouldn't I be recording from a compressed video already?

    What I mean is if I recorded at 12Mb/s I wouldn't I get better quality directly from the satellite as opposed to a recorded stream from the PVR?
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    Originally Posted by Christopher2222 View Post
    When I record a show on the PVR using the HD6400 Bell receiver I would think it's hardware encoded H.264 with some predetermined bitrate. A 2Tb drive allows me to record about 500 hours of HD programming. Converting that into a bitrate that works out to 8.88 Mb/sec.

    So if I record from the recorded show, Wouldn't I be recording from a compressed video already?

    What I mean is if I recorded at 12Mb/s I wouldn't I get better quality directly from the satellite as opposed to a recorded stream from the PVR?
    The video from HDMI should contain same amount of compression artifacts whether you are viewing a real-time broadcast or a recording of that broadcast.

    Satellite TV broadcasts in N. America use H.264 for video, which means the video is already compressed before it is even transmitted. A satellite provider's DVR function typically records the broadcast H.264 transport stream to its hard drive as is, without further transcoding. This means the audio and video in the recording and the audio and video in the real-time broadcast are exactly the same.

    If you could copy the recordings directly from the receiver's hard drive, you'd have the best possible quality, but the system is designed to prevent that. Recordings are encrypted and often broken into many small pieces
    Last edited by usually_quiet; 29th Jan 2018 at 13:55.
    Ignore list: hello_hello, tried, TechLord
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  3. Originally Posted by usually_quiet View Post
    A satellite provider's DVR function typically records the broadcast H.264 transport stream to its hard drive as is, without further transcoding.
    There must be some kind of transcoding. Being able to fit 500 hours on a 2 Tb hard drive suggests it was coded at 8.88 M bits/second. Which would mean if I captured any higher than 8.88 I would just be wasting bits. It would also mean the blue ray dvd's are of better quality than any satellite broadcast I could transmit through my receiver. Perhaps I am wrong about that?
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  4. Originally Posted by Christopher2222 View Post
    Being able to fit 500 hours on a 2 Tb hard drive suggests it was coded at 8.88 M bits/second. Which would mean if I captured any higher than 8.88 I would just be wasting bits.
    No. Every time you reencode with a lossy codec you get worse results. The higher the bitrate you use the less worse it gets.

    Originally Posted by Christopher2222 View Post
    It would also mean the blue ray dvd's are of better quality than any satellite broadcast I could transmit through my receiver.
    Decent Blu-ray video is far better than anything you get via satellite.
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  5. Originally Posted by Christopher2222 View Post
    There must be some kind of transcoding. Being able to fit 500 hours on a 2 Tb hard drive suggests it was coded at 8.88 M bits/second.
    The transcoding already happens at the TV station/broadcast station before it is sent into orbit. Your receiver simply stores the data it is receiving without recompressing it again.


    Originally Posted by Christopher2222 View Post
    Which would mean if I captured any higher than 8.88 I would just be wasting bits.
    If you re-encode a lossy 8 Mbit/s file to a lossy 8 Mbit/s you will have quality loss. Even if you encode to 20 Mbit/s you will have quality loss (but less quality loss than if you encode with 8 Mbit/s - so it can make sense to use more bitrate). EVERY re-encoding with a lossy codec, no matter the bitrate, will reduce the quality further (*). Sometimes will call that "Generation loss".
    So the best is always to not re-encode but to simply copy 1:1. Like said earlier this isn't always possible because of DRM.

    Originally Posted by Christopher2222 View Post
    It would also mean the blue ray dvd's are of better quality than any satellite broadcast I could transmit through my receiver.
    That is usually true but because of other reasons: DVDs and Blu-Rays don't have to be encoded in real-time. The authoring houses can put more effort into the encoding and mastering. And of course Blu-Rays have bitrate than your typical TV broadcast.


    ((*) Well, you lose information with every generation. You can however try to filter certain compression artifacts out so the end-result might look better than the original to a human. This requires more effort and knowledge than straigt re-encoding.)



    /edit:
    jagabo was faster...
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  6. ok yes agreed recording a lossy recording using a lossy codec gets even worse. Now isn't that just for composite video?

    However, looking at it slightly differently .... if it were HDMI video that has a specific number of bits being played per per second 8.8 Mbits/second (isn't that digital) even if it were a lossy codec recording the same 8.8 Mbits/second you wouldn't loose anything .. that's me thinking in digital terms. Thinking analogously it's of course going to loose out I understand that but writing this out I'm thinking I'm all wrong about HDMI.
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  7. Originally Posted by Christopher2222 View Post
    ok yes agreed recording a lossy recording using a lossy codec gets even worse. Now isn't that just for composite video?
    No, it's for all digital video. Take a smooth piece of aluminum file. Randomly wad it into a 1 inch ball (compress it). Open the ball back up (decompress it). Notice all the wrinkles (compression artifacts)? Now wad it up again, but into a 2 inch ball (compress it again, but less than the first time). Open it up again (decompress it). Does it have more wrinkles than before? The same? Less? It has more wrinkles, of course. Every decompress/recompress cycle adds more artifacts.

    Originally Posted by Christopher2222 View Post
    However, looking at it slightly differently .... if it were HDMI video that has a specific number of bits being played per per second 8.8 Mbits/second (isn't that digital) even if it were a lossy codec recording the same 8.8 Mbits/second you wouldn't loose anything .. that's me thinking in digital terms. Thinking analogously it's of course going to loose out I understand that but writing this out I'm thinking I'm all wrong about HDMI.
    HDMI only transmits uncompressed video. This is not a file copy. The satellite box is decompressing the video (whether it's live or recorded on its hard drive) before sending it over the HDMI cable. Your Colossus captures that uncompressed video and compresses it again. No matter what bitrate you use you will lose more quality.
    Last edited by jagabo; 29th Jan 2018 at 21:05.
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