Compressing h.264 recordings?

[SageGk]

I tried to compress a 1 hour h.264 recording to a .avi file and it was taking a VERY long time and the status was at 134% complete. Is this a known problem? or is the progress indicator just out of whack with these files?

[kbyrd]

Originally Posted by SageGk

I tried to compress a 1 hour h.264 recording to a .avi file and it was taking a VERY long time and the status was at 134% complete. Is this a known problem? or is the progress indicator just out of whack with these files?

What are you trying to do? Can you be more explicit? H.264 is already very compressed, I believe you mean transcode. AVI isn't a compression format, it's just a container. The AVI contains and audio stream and a video stream each of which can be different formats. H.264 is a video format, it needs to go in a container like mp4 or mkv or avi (I don't know if AVI supports H.264)

Is the destination file getting bigger?

[SageGk]

Yes, I meant that I would like to transcode it. My goal is to archive a h.264 recording as a smaller file to save space. Sorry, I deleted the conversion file already so I cannot answer your questions.

[kbyrd]

What are you converting it to? I expect that it can take a very long time. I doubt anyone can tell you about the progress bar unless we know what software you are using to do the transcoding and made what the final format (what goes in the AVI?) is.

On my system encoding to h.264 runs can run at about 1/2 real time (transcoding a 1hr video takes 2+ hours), it really depends on what encoding you're using for the destination format.

[SageGk]

Originally Posted by kbyrd

What are you converting it to? I expect that it can take a very long time. I doubt anyone can tell you about the progress bar unless we know what software you are using to do the transcoding and made what the final format (what goes in the AVI?) is.

On my system encoding to h.264 runs can run at about 1/2 real time (transcoding a 1hr video takes 2+ hours), it really depends on what encoding you're using for the destination format.

The default HDTV deinterlaced avi setting.

[kbyrd]

Ok, this must be from within SageTV and not an external transcoding app. I'm out of help for you then. I've never done this inside SageTV. I'll step aside and let someone else give it a shot.

[evilpenguin]

Its not built in Sage, but Handbrake 9.3 apparently does a good job with HD-PVR files.

[mayamaniac]

The default SageTV trancsoder converts the recordings to MPEG4, which is almost the same as H264. So it's pointless to do so as H264 is already compressed. It's kinda like taking a zip file, and zipping it again.

I think the only way you reduce the filesize is if you converts to a lower resolution than the original H264 recordings, like 1080 to 720.

[joe123]

Is anyone here converting h.264 (.ts) files to other formats to save on disk space and still getting as good quality as the original h.264?

From reading replys, it sounds like h.264 recordings are as compressed as they can possibly get and any further compression will result in a degradition in video quality.

Is this the general understanding?

I would like to compress h.264 more if it's available, but not at the expense of a reduction in video quality. So I am cheking to make sure I understand correctly.

[Oats]

Any time you compress it is going to lose quality. I would manually record a 2 min clip and try transcoding it with different quality settings to find a quality to size ratio that is acceptable. Then use those settings to transcode full shows.

[bits]

Originally Posted by mayamaniac

The default SageTV trancsoder converts the recordings to MPEG4, which is almost the same as H264. So it's pointless to do so as H264 is already compressed. It's kinda like taking a zip file, and zipping it again.

I think the only way you reduce the filesize is if you converts to a lower resolution than the original H264 recordings, like 1080 to 720.

Changing the resolution will have an insignificant effect on file size. To change file size you need to lower the bitrate.

If you want smaller files then record with a setting that uses lower bitrate. Re-encoding will result in PQ loss and will introduce other unwanted artifacts. Another approach would be to add HDD space and be more selective in what you keep.

[sandor]

Originally Posted by bits

Changing the resolution will have an insignificant effect on file size. To change file size you need to lower the bitrate.

If you want smaller files then record with a setting that uses lower bitrate. Re-encoding will result in PQ loss and will introduce other unwanted artifacts. Another approach would be to add HDD space and be more selective in what you keep.

with 2 TB single drives going for $160, buy more space. it is cheaper than the time it will take to re-encode an already well compressed video.

http://www.newegg.com/Product/Product.aspx?Item=N82E16822145276&cm_re=2_TB-_-22-145-276-_-Product

[autoboy]

h.264 is as good as it gets. You can only reduce the bitrate and sageTV's mpeg4 codec is not as good as the h.264 codec from your HD-PVR so you will get less picture quality for the same bitrate with sageTV's codec. What you can do though, is adjust the default recording quality from the HD-PVR to a lower bitrate and all your recordings will save space.

[joe123]

Thanks to all with the suggestions. I have about 6TB of recordings in SD .avi format - all are SD mpg recordings that were later compressed to .avi format.

Now that I got into HD recordings, the disk space requirement went up by a factor of 6-8x times

So it looks like I need to trim down my recordings and add 2TB disks as well.

By the way the reason I compressed my SD recordings, was that the compression was not noticible for me going from .mpg to .avi. A lousy SD recording is still a lousy recording when compressed.

With HD, it's a whole different story. The images are so supperior, that I don't want to compress since I will be losing image quality as folks have said here.

[Fuzzy]

I think what you aren't realizing is that those HD recordings already ARE compressed with pretyt much the best codec available (H.264). You will not get acceptable results going with anything else. Now.. what you MIGHT be able to do is actually lower your HD-PVR's recording quality setting, as you may have it turned unneccesarily high. I do know that my HD streams I get from Dish Network (R-5000) are mostly about 5Mbps, and the quality is quite acceptable. Admittedly, they probably have better encoders than the HD-PVR, but I'd say 6-7Mbps H.264 would be more than sufficient.

[joe123]

Originally Posted by Fuzzy

I think what you aren't realizing is that those HD recordings already ARE compressed with pretyt much the best codec available (H.264). You will not get acceptable results going with anything else. Now.. what you MIGHT be able to do is actually lower your HD-PVR's recording quality setting, as you may have it turned unneccesarily high.

Hi Fuzzy. I am new to the HD world, so I am learning. What I wanted to know was if h.264 could be further compressed without any loss in quality and now I know the answer - which is no.

As for lowering the HD-PVR recording quality - yes, that's the other option, execpt that I want to get the best picture I can, so I have it set as high as it goes.

My TimeWarner box can output in 480i/p, 740p, and 1080i. I noticed that the HD-PVR will record accordingly, so that a 740p movie coming from my TWC cable box will take up less disk space than a 1080i movie ( correct me if I am wrong ).

So if the above is true, that the HD-PVR records according to the feed it receives, and you wanted the best HD recording possible, you would then tell SageTV to record at the highest possible recording for the HD-PVR. No?

[Fuzzy]

My point was that there is a point as you go up in bandwidth, that the returns are negligable. Having it to max is probably not the best option, and is needlessly wasting disk-space. I'd spend sime time and try reducing it down through the different settings to see at what point you notice a drop in quality, and stop there. My guess is you'll be able to save some decent space.

Also realize that the video from the cable company is already somewhat degraded to save broadcast room. You then recording it and trying to get a higher quality by choosing the max setting isn't really going to do much for you.

[joe123]

Originally Posted by Fuzzy

My point was that there is a point as you go up in bandwidth, that the returns are negligable. Having it to max is probably not the best option, and is needlessly wasting disk-space.

Got it. I have been told and as you noted, that TimeWarner has lousy feeds and that DirecTV / Dish / AT&T Uvers all have much better image qualities.

Is there a thread on which service providers offer the best service (channels) for the money? I may soon leave TWC after some 15 years.

[Fuzzy]

Not really, becaues it is way to hard to sum up. 'Best Service' varries quite a bit, based mostly on your tastes. Also, the offerings varry greatly from area to area. Your best option, if price is your primary concern, is figure out a list of the channels you want, and see which package from each provider includes those.

As for feed quality, that will also varry from area to area, and even within a service, from channel to channel, and is subject to change frequently. They quite often will move channels between transponders/frequencies, and squeeze some channels a little more to make more fit. It's the nature of the business right now, that they are trying to get more and more channels into the same stream.

Also, there are differences in equipment options, as well as sagetv interfacing options. Cable providers boxes can usualy be controlled via Firewire. DirecTV can be controlled via serial/usb. Dish has neither option, but DOES have configurable remote addresses, so a single blaster can control MANY boxes. Then there are the actual recording mechanisms. With cable, you may be able to get a decent amount of channels via QAM, or perhaps firewire will work for you. With DirecTV, your pretty much limited to the HD-PVR. With Dish, you can use the HD-PVR, or, if you choose to spend the moneym, can go with the R-5000 in an older ViP-211 STB. Again, there are a LOT of criteria out there, so there's no way to determine who offers the best service.

[stanger89]

Yeah, for example in my area, cable doesn't hold a candle to Dish or DirecTV. With either Satellite provider you can get pretty much all the major networks in HD. There's only I think two networks I ever record from anymore that aren't broadcast in HD on Dish.

If I had Cable, in addition to having the worst provider in the country , I'd have significantly less HD.