# SD vs HD MPEG4 Disk Usage



## derousse (Apr 25, 2007)

So now that we have TLC in HD, I have a question.

My wife records a number of programs on TLC and she could care less if they are in HD or not (I know - I don't understand it either. . .). Anyway, I understand that MPEG4 does a great job of compressing HD. So what will occupy more disk space , an SD recording, or a recording of the exact same show on the new HD MPEG4 channel?


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## Rob Glasser (Feb 22, 2005)

These are very rough numbers, based on some events I've seen on my external drive:

1 hr of MPEG2 SD = approx 1 GB
1 hr of MPEG2 HD = approx 4 - 5 GB
1 hr of MPEG4 HD = approx 2 - 3 GB

Every event is slightly different depending on the content and compression rate, your results may vary. For example, a PPV movies, especially HD, are going to take up more space as there appears to be less compression. OTA events are also going to typically take up more space.


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## Antibus (Dec 17, 2005)

Rob Glasser said:


> These are very rough numbers, based on some events I've seen on my external drive:
> 
> 1 hr of MPEG2 SD = approx 1 GB
> 1 hr of MPEG2 HD = approx 4 - 5 GB
> ...


OTA broadcasts typically use 12 to 15 Mbits/sec for their HD channel. This equates to about 5 to 7 GB for 1 hour.


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## BobMinn (Jul 1, 2005)

In just got a usb drive working and my numbers for file sizes agree with the above. 

This says that my 500gb drive will hold about 100 hours of mpeg-2 and 200 hrs of mpeg-4 hd. If this is true, why does the vip622 320gb drive only hold 30 hours of hd, is there a lot of overhead?

Bobminn


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## tnsprin (Mar 16, 2003)

BobMinn said:


> In just got a usb drive working and my numbers for file sizes agree with the above.
> 
> This says that my 500gb drive will hold about 100 hours of mpeg-2 and 200 hrs of mpeg-4 hd. If this is true, why does the vip622 320gb drive only hold 30 hours of hd, is there a lot of overhead?
> 
> Bobminn


Most of the 320GB drive is not made available to you for your video. Someone posted the full details somewhere. Among other things 100GB is reserved for Dish on Demand. Some partitions are reserved for the operating system, others for system logs, and even one for your multimedia.


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## Moridin (Mar 22, 2005)

BobMinn said:


> why does the vip622 320gb drive only hold 30 hours of hd, is there a lot of overhead?


One must also consider that the hours capacity is an estimate based on MPEG-2 file sizes. If the menu shows that I have 25 hours of HD storage available and I record 1 hour of MPEG-4 programming, the menu might then say that I have 24 hours and, say, 20 minutes of HD storage available.


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