How much disk space per minute with MPEG-4

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davebullet

6 posts

Wannabe Geek

#85800 25-Jun-2011 09:13

Sorry for the dumb, easy question, but for most DVB-T receivers that encode and store using MPEG-4, how much disk space is consumed per minute of recorded material off our main channels?

This might be a "how long is a piece of string?" question, so I'm after a range (will do).

What I'm trying to determine is whether I'm better off with a receiver with built in HDD, or simply PVR capability with a large USB stick (all I really want is about 9 hours of recording to match my paultry current VCR system and 3 tapes :-)

B1GGLZ

1961 posts

Uber Geek

#485677 25-Jun-2011 09:32

It really depends on what is being transmitted (HD vs SD) and it varies.
I'm using a Hauppage HVR-2200 in my PC and the last couple of days I recorded 1 hour 10 mins from Prime which used 1.35gb and 1 hour 2 mins TV One used 4.98gb.

So around 1gb per hour SD and 5gb per hour HD in my case

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Behodar

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#485678 25-Jun-2011 09:36

HD channels are approximately 10 Mb/s each so that's 75 MB/minute. SD channels are about a quarter of that.

Edit: My figures may be a little off, just looked at Four and it's sitting around 4.5 Mb/s for SD. TV3 is mainly around 10 Mb/s but I've seen it jump up to 15.

Deev8

481 posts

Ultimate Geek

#485820 25-Jun-2011 17:34

I had a look at the size of recordings from TV One, TV2, TV3, Four and Prime recently. I took the file sizes of 6 recordings of approximately one hour each from each channel, and taking the exact length of each recording into account calculated the file size per hour of recording.

TV One averaged 3.5GB per hour but varied between 3.3 and 3.9 GB per hour.
TV2 averaged 3.3GB per hour but varied between 3.1 and 3.6 GB per hour.
TV3 averaged 4.4GB per hour but varied between 4.2 and 4.8 GB per hour.
Four averaged 1.9GB per hour with all 6 recording very close to 1.9 GB per hour.
Prime averaged 1.2GB per hour but varied between 1.0 and 1.4 GB per hour.

lchiu7

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#485982 26-Jun-2011 10:53

Deev8: I had a look at the size of recordings from TV One, TV2, TV3, Four and Prime recently. I took the file sizes of 6 recordings of approximately one hour each from each channel, and taking the exact length of each recording into account calculated the file size per hour of recording.

TV One averaged 3.5GB per hour but varied between 3.3 and 3.9 GB per hour.
TV2 averaged 3.3GB per hour but varied between 3.1 and 3.6 GB per hour.
TV3 averaged 4.4GB per hour but varied between 4.2 and 4.8 GB per hour.
Four averaged 1.9GB per hour with all 6 recording very close to 1.9 GB per hour.
Prime averaged 1.2GB per hour but varied between 1.0 and 1.4 GB per hour.

I am guessing that TV3 uses more data because it has two audio tracks and possibly a higher video bitrate?

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sbiddle

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#485995 26-Jun-2011 11:25

davebullet: Sorry for the dumb, easy question, but for most DVB-T receivers that encode and store using MPEG-4, how much disk space is consumed per minute of recorded material off our main channels?

This might be a "how long is a piece of string?" question, so I'm after a range (will do).

What I'm trying to determine is whether I'm better off with a receiver with built in HDD, or simply PVR capability with a large USB stick (all I really want is about 9 hours of recording to match my paultry current VCR system and 3 tapes :-)

To clarify things a little in the DVB world hardware doesn't do any decoding/encoding when it records data.

A PVR will simply dump the MPEG transport stream straight to the HDD without modifying it in any way, and it doesn't pay any real attention to the video format as it may be MPEG2 or MPEG4/H.264. All the work is done by the device when it plays back a video. Actual space will depend entirely on the bitrate used by the broadcaster.

Most of the cheap STB's are IMHO a total waste of time. No MHEG5 EPG support and many use FAT32 for USB drives which means splitting files up.

nigelj

856 posts

Ultimate Geek

#486011 26-Jun-2011 12:22

Deev8: TV One averaged 3.5GB per hour but varied between 3.3 and 3.9 GB per hour.
TV2 averaged 3.3GB per hour but varied between 3.1 and 3.6 GB per hour.
TV3 averaged 4.4GB per hour but varied between 4.2 and 4.8 GB per hour.
Four averaged 1.9GB per hour with all 6 recording very close to 1.9 GB per hour.
Prime averaged 1.2GB per hour but varied between 1.0 and 1.4 GB per hour.

This seems to be fairly representative but maybe a bit low compared to my recordings... A couple of Prime Time examples (so likely HD for TV1/2/3)

Recording from TV One (Swing Vote) 2 hrs 29 mins = 11GB (~4.4GB/hr) - Although a Sherlock recording was only 6GB for 2 hours (3GB/hr)
TV 2 ($#*! My Dad Says) 35 mins = 2.2 GB (~4GB/hr)
TV 3 (House / Inside New Zealand) ~1hr 5mins = 4.5-4.9GB

FOUR seems pretty consistent at ~2GB/hr from my experience, and Prime about 1 GB/hr pretty consistent.

bfginger

1237 posts

Uber Geek

#486240 26-Jun-2011 23:29

The old Freeview|HD 720p demo channel ran at about 2.2gb/h towards the end. 720p seems more tolerant of lower bitrates than 1080i.

I've seen TV1 go well over 5gb/h when the other 3 channels have been mostly idle.