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AVCHD bitrate needed to approximate MPEG2 bitrate

Mar 13, 2012 12:01 PM

Is there a way to estimate the needed AVCHD bitrate to approximate the quality of MPEG2 bitrate of the same material (typically fast moving sports)?

 

In other words, what AVCHD bitrate would approximate MPEG 2 @ 35mpbs, MPEG 2 @ 50 mbps (fast moving sports)?

 

Thanks.

 

-wolv

1286 Views   9 Replies   Latest reply: Jim Simon, Mar 13, 2012 8:15 PM
 
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  • John T Smith
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    1. John T Smith,
    Mar 13, 2012 12:28 PM   in reply to wolverine.ks
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    I think that is going to depend on the features of your camera

     

    For my Canon Vixia HFS100 I film in 1920 x 1080 60i FXP 17Mbps (I don't use the 24Mbps setting because my end result is a DVD, so I'm going to have to down-rezz anyway)

     
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  • Jim Simon
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    2. Jim Simon,
    Mar 13, 2012 2:35 PM   in reply to wolverine.ks
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    The general rule is half.  MPEG4 at 25 Mbps will have about the same quality as MPEG2 at 50 Mbps (all else being equal).

     

    That is a very loose rule of thumb, however.  There are a lot of factors at play here that give MPEG 4 certain advantages that MPEG 2 will never have.

     

    Here's some good reading.

     

    "So -- conclusions? Easy -- AVCCAM's 21mbps PH mode is a clearly superior codec over XDCAM EX. No question, no argument, no doubt."

     

    http://www.dvxuser.com/articles/article.php/25

     
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  • Jim Simon
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    3. Jim Simon,
    Mar 13, 2012 2:33 PM   in reply to John T Smith
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    I don't use the 24Mbps setting because my end result is a DVD, so I'm going to have to down-rezz anyway

     

    That's very odd thinking.  Higher bitrates mean better quality.  Where the footage ends up is largely irrelevant.  You pretty much always want to start out with the highest quality possible

     
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  • John T Smith
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    4. John T Smith,
    Mar 13, 2012 3:35 PM   in reply to Jim Simon
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    I started with the 17Mbps setting the 1st time I used the camera... and, since the DVD's I produce are much better than when I used an SD only workflow, I've just never bothered to change

     

    I may, someday, try 24Mbps and then compare two different DVD's to see if I notice any difference... If I do that, and I do notice a difference, I'll adjust my thinking

     

    Until then, my thought (example here, not real numbers) is that if I am going to downrez from 17 to 10 I am not likely to notice much of a difference going from 24 to 10

     

    If I had a BluRay drive... I would agree to start with the higher bitrate

     
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  • wolverine.ks
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    5. wolverine.ks,
    Mar 13, 2012 3:51 PM   in reply to Jim Simon
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    so in general, there would be virtually no difference in the quality between 24 mbps AVCHD and 50 mbps MPEG2?

    but 24 mpbs AVCHD could be slightly better than 35 mpbs MPEG2?

     

    Thanks.

     

    -wolv

     
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  • wolverine.ks
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    6. wolverine.ks,
    Mar 13, 2012 4:05 PM   in reply to Jim Simon
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    additionally, it appears that the codec was most stressed and likely to break with lots of motion. would that mean AVC codecs are better with things like fast moving sports than MPEG2 would be?

     

    Thanks.

     

    -wolv

     
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  • Christian Jolly
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    7. Christian Jolly,
    Mar 13, 2012 8:10 PM   in reply to wolverine.ks
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    would that mean AVC codecs are better with things like fast moving sports than MPEG2 would be?

     

    Yep, pretty much in all ways, AVCHD beats MPEG-2 based camcorders. It's about 10 years younger as a video technology so there are lots of tweaks. AVCHD is able to do more with less - about 50% less as indicated here on this thread.

     
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  • Jim Simon
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    8. Jim Simon,
    Mar 13, 2012 8:10 PM   in reply to wolverine.ks
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    Yep.

     
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  • Jim Simon
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    9. Jim Simon,
    Mar 13, 2012 8:15 PM   in reply to John T Smith
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    if I am going to downrez from 17 to 10 I am not likely to notice much of a difference going from 24 to 10

     

    Still odd thinking.  Recording at 17 will give you more artifacts and encoding errors than recording at 24.  Again, where it ends up is not relevant.  The source will be better, so the end result, whatever it may be, will also be better.

     

    Now, whether or not those extra artifacts are noticeable is a separate issue.  Without a lot of fast moving action, or if your TV is small enough, they might well not be.

     

    My point was only that the reasoning was a bit off.  Ideally, you always want to start with the best quality source you can.

     
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