Reducing size of an MPEG to create 80 min VCD

[tatayet]

Oh Dear ... I can imagine that question was asked several times, already ... and I found some answers already but ...

my question is simple : I have one Mpeg movie file that is longer than 80 minutes (Let's say 1h50). How to I compress that file to be able to burn a VCD afterwards ?

I saw some posts with lots of things to modify in TMPGEnc ... but I don't like changing parameters I don't know about ...

Could someone come with a procedure to compress my MPEG (Possibly create a smaller MPEG file), and explain the steps to me ?

Many Thanks !

[Pnx]

have you consider the possibility of make 2 mpeg files???

[tatayet]

No ... I'd like to put 1 movie (1 MPG file) on my VCD.
Any idea how to "compress" my MPG file to make it 800MB (Size of my CD ...)

Thans !

[Pnx]

In that case i cannot help sorry

[pieroxy]

If your file is a MPEG1 file, then it is trivial. The only complication is to find the final bitrate:

1h50min = 6600s
CD=795MBytes [*8*1024]=6512640kbits
Final bitrate=986kbits/s

1. Open your file in TMPGEnc
2. Load the right VCD template (PAL or NTSC)
3. Load unlock.mcf
4. Edit your settings and change the video and audio bitrate so that their sum is 986kbps.
5. Check that "Motion Search Precision" is set to MAXIMUM QUALITY (You'll need it at this low bitrate) - Under the tab Video
6. Make sure that the "Soften Block Noise" is checked (You'll need it at this low bitrate) - Under the tab Quantize Matrix
7. Hit Encode

Let me know if you need anything more. Note that point 5 and 6 are optional, it is just to make sure you have the best quality out of your MPG file.

[atifsh]

if u going to use this mpeg once or twice its ok otherwise 1150(vcd standard) is already pretty bad going below will make it even worse.

[tatayet]

Ok ...

What is that "unlock.mcf" ?
Is that a file coming with the TMPGEnc ?
What is that used for ?


What is the bitrate ? (Is that a kind of pictures / second ?

How do you come to 986 kbits/sec ?

I was thinking it would be easier to compress an MPG file !!!

[pieroxy]

What is that "unlock.mcf"

It is a template file you can load through the "Load" button in the main screen of TMPGEnc.

Is that a file coming with the TMPGEnc ?

Yes. It is located in the install directory of TMPGEnc, under Templates\Extra.

What is that used for ?

When you load VCD-PAL.mcf (template) most of the fields, such as the bitrate, are disabled, because they are fixed in the standard. You need to load unlock.mcf in order to change them. So, that means you are going to burn a VCD that is not compliant. It should play in most of the VCD players out there though.

What is the bitrate ? (Is that a kind of pictures / second ?

Almost. It is the number of bits per second that your MPEG file is going to consume. The higher the bitrate, the higher the quality of your MPEG, but the bigger your final file. It is a tradeoff.

How do you come to 986 kbits/sec ?

I compute how many seconds my movie is, and how many kbits I want to use for it. Than I divide the kbits with the seconds, and I get kbits/sec. In my example: 6512640/660 = 986.
This include both audio and video. For such a low bitrate, I would recommend 128kbit/s for the Audio, in Joint-Stereo mode and then 858kb/s for the video.

I was thinking it would be easier to compress an MPG file !!!

If you think about it, it is pretty easy . I mean, you need to compute a division, for which all Operating System will provide a simple calculator for. Then you need a 10 click procedure in TMPGEnc. How much simpler can it get?

[atifsh]

Originally posted by pieroxy
How much simpler can it get?

how bout already burnt vcd/dvd

jokin.........

[tatayet]

Seems easy, indeed, with that unlock.mcf file ...
I need to try that ...

what do you mean by "Joint Stereo" mode ? Is that something I need to select in TMPGEnc ?

Latest question ... Do you have an estimate of the Video and Audio Bitrate from which we have "bad performance" ?

Many thanks !

[tatayet]

ok - cool ...

I guess the unlock file allows me to unlock so that I can change the settings (Bitrate ...).
And the Template file allows to load the right parameters directly (PAL, etc etc ...)

- It seems like I have different template files for PAL (For VCD) ... one in the main directory, and one in the Extra directory ... any difference ?
- How do I know the final size of my MPG file to be burned ? I can only know that with your calculation above ??

Thanks !

[pieroxy]

I guess the unlock file allows me to unlock so that I can change the settings (Bitrate ...).
And the Template file allows to load the right parameters directly (PAL, etc etc ...)

That's right

It seems like I have different template files for PAL (For VCD) ... one in the main directory, and one in the Extra directory ... any difference ?

The one in the extra directory allocate a little more bitrate to the video and a little less to the audio, resulting in the same overall VCD bitrate: 1374kbps. This template is not compliant with the VCD standard, but result in a VCD that plays in most set-top players.

- How do I know the final size of my MPG file to be burned ? I can only know that with your calculation above ??

The resulting file size is the size of your media (CD) in mode 2. 74minCD=740MB, 80minCD=800MB, 90minCD=900MB... I always leave out 5 MB to make sure I don't get over the capacity by mistake.

what do you mean by "Joint Stereo" mode ? Is that something I need to select in TMPGEnc ?

Yes it is, in the "Settings" dialog box on the "Audio" tab. Not sure it is supported by all VCD players though...

Do you have an estimate of the Video and Audio Bitrate from which we have "bad performance" ?

The VCD standard pretty much sets the minimum for me. It is already pretty bad, so I would not recommend lowering it.

Of course, there is no "Universal" answer to this question. For a NTSC full screen video, the VCD bitrate for the video (1150kbps) is pretty much the minimum. Now if you have black bars (widescreen movie) you can probably get the bitrate a little bit under that while retaining the same quality since the black bars are not going to consume a lot of bits.
For the audio, it is MPEG-1 layer2, so 128kbps is probably pretty bad already.

My recommendation is the following:
1. Select a small sample of your movie
2. Encode it using different bitrates for both audio and video
3. Burbn a VCD on a CD-RW with all the different segments
4. Judge by yourself.

The reason I can't recommend anything else is that the result could vary greatly if the VCD is to be played on a PC, on a VCD player, on a huge TV, on a good stereo... You'll have to make your own judgement as to what compromises you are ready to make to get this movie on one CD. We are all different and have a different threshold on quality.

I usually try to never compromise on the quality of my VCDs/SVCDs/DVDs/MP3s because if I know on which equipment I am watching them today, I never know what I will have in the future. And nothing would irritate me more than having to throw everything away because my HHHDTVMax3000PlusEnhanced that I'll buy in 50 years will show these huge blocks I was having trouble to see on my 20 inch TV today.

[atifsh]

Originally posted by pieroxy

74minCD=740MB,
80minCD=800MB,
90minCD=900MB...

is'nt.....................
74min = 650mb
80min = 700mb
90min = 800mb [never seen these]
99min = 870mb [i hav these in use]

[pieroxy]

In mode 1 (CD-ROM mode):
74min = 650mb
80min = 700mb
90min = 800mb [never seen these]
99min = 870mb [never seen ot tried these either]

In mode 2 (VCD-SVCD mode) and CD-Audio mode:
74minCD=740MB,
80minCD=800MB,
90minCD=900MB...

If you think about it:
80 min of audio, is 4bytes/sample at 44100Hz, that is:
- 44100x4=176400 bytes/sec
- 176400*60*80=846720000bytes/80min
-> There you go, 846720000B = 826875KB = 807MB.

[tatayet]

ok ... Thanks for the information !!!