Bitrate related Questions?

[Yalgaar]

1) Can I calculate the bitrate of a particular file manully? What is the formula?

2) What is an acceptable bitrate to watch a video on a 29 inches TV?

3) I have heard something like VHS like bitrate, what does that mean?

4) I know that when I watch VHS on my TV and when I watch the original DVD's on my TV, I do not notice much difference. What does that mean?

Thanks in advance

[blutach]

See the Compression Explained FAQ - link in my signature.

As to #4, it means they are trashy quality DVDs or extremely high quality VHS (since the bitrate for VHS is about 1,500 Mbps or less). Or that your TV is just not big enough to display the difference.

Regards

[Taelon]

To see the bitrate of a DVD or .VOB file try this tiny utility

The best S-VHS quality bitrate will be well under 4Mbps
The best DVD quality bitrate is up to 10Mbps (peak), about 7-8Mpbs average

If you can't notice any difference on your 29" TV it could be that you just haven't trained your eyes/brain to notice the differences in grain, sharpness, etc. or you just might need glasses

[blutach]

Noting that utility includes the audio and does not output the video BR only.

Regards

[Tupac]

yalgaar, you might also like to know that "7-8Mbps" does not mean megabytes per second, as in computers, but megabits per second, which is much smaller

[blutach]

@Tupac - although your advice is sound, may I ask you to read rule 2. I'm sure your signature is offensive, not just to anonymez but also to others. Please change it.

Thank you.

Regards

[anonymez]

@yalgaar: are you sure you don't notice any quality difference between a dvd and vhs? that could be a problem!

an acceptable bitrate on a 68cm (close enough to 29") tv IMO is ~3000-4000kbps video. this is only the case when using a high quality encoder, like tmpgenc, mainconcept or when using dvd rebuilder. audio quality depends on your sound system

@blu: thanks, this 'tupac' was on another forum, where many of his/her posts were completely incorrect (we believe on purpose), and became rude when contradicted. he/she was permanently banned for wasting people's time, and i guess i was recognized by this person because my sigs were identical here and there. my other sig has been changed now

[Yalgaar]

bitrate theory

Is there a way to calculate the bitrate manually by just diving the size of vob file by the time of the file.

I mean would it be right way to just size/time and find it in kb/s?

We can very easily find the size of the .vob files from windows explorer. We can then very easily find the length of the .vob title by just playing it.

Example: If we find out that the size of one of the vob file is 1GB and the length of the video is 1 hour.

Would it be right to calculate it this way?

1GB = 1,000 MB = 1,000,000 KB = 8,000,000Kbits

AND

1 hour = 60 min = 3600 sec.

Now to find out kbit/s for the vob file we just do:

8,000,000/3600 = 2222kbits/s


Is this right theory??


Thanks

[blutach]

No - you need to subtract off the audio at the rate it is recorded (e.g. 5.1 channel AC3 is often 384 or 448 kbps) and the subtitles (about 5 Mb per stream off the top). Just use the calculators - they are very easy.

Get length and size of title from DVD Shrink. Understand what audio you have (2ch = 192kbps, 5.1 as above) and how many streams.

Regards

[Yalgaar]

No - you need to subtract off the audio at the rate it is recorded (e.g. 5.1 channel AC3 is often 384 or 448 kbps) and the subtitles (about 5 Mb per stream off the top). Just use the calculators - they are very easy.

Get length and size of title from DVD Shrink. Understand what audio you have (2ch = 192kbps, 5.1 as above) and how many streams.

Regards

Will substracting 2222 - 400 = 1822kbits/s an approximate kbps? (while I substract the audio kbits out of it)

Is 5MB of subtitle for the whole title? In that case it should hardly affect the average assuming hug file size and substracting 5 MB out of it.

I am not looking for a exact kbit rate here. 10-15% of variation is OK. Just want an idea on how it applies.

[blutach]

No, as there is also something called the MPEG overhead to consider.

Is there a problem using the calculators built in to IfoEdit and vcalc and even Videohelp's online tool?

Regards

[Yalgaar]

No, as there is also something called the MPEG overhead to consider.

Is there a problem using the calculators built in to IfoEdit and vcalc and even Videohelp's online tool?

Regards

Don't know if there is a problem, just found out confusing when attempted to use it for the first time and was looking for a easyier method. Anyway now will try them, which one would you suggest is the easiest one and also one which will be able to tell me bitrate of individual files from the original DVD itself as well as files stored on the hard disk.

Thanks

[blutach]

The one in IfoEdit is easiest. Since the files stored on the hard drive will be identical in bitrate to those on the DVD, there is no need to do anything different. Input the data as I have described above and in the FAQ.

Regards

[Yalgaar]

Question for Blutach and Taelon

I tried "IfoEdit" and "DVD Bitrate Viewer"


Is there anything other utility which does both.

I mean DVD Birate viewer does not calculate bitrate for files stored on my HDD. It can ONLY do it for real DVD's in the drive.

IFOedit, will do it only if I enter details manually and I have to open Shrink and wiat for 1-2 min till Shrink opens the DVD files. I want it automatic.

Is there any program which will do it automatically and which will do for DVD files on the HDD and also from the DVD itself in the drive?

Thanks a lot, I really appreciate it. Finally the bit rate thing is getting in my head. LOL