Increase the bitrate---> Lose Quality?

[mark63534]

I'm trying to make a AVCHD DVD5 out of a 2GB MKV. So far, I've been looking all around the web, and all I've found is that is you increase the bitrate, the quality will get better.

I already know that is a myth.

So, the real question is... If I reconvert the mkv to avchd, will I lose quality although the bitrate will be increased?

(I'll be using multiavchd for this project.)

[videopoo]

Whenever you encode / transcode a compressed format to another, you'll most likely lose quality no matter the bitrate

[edDV]

Post mediainfo (view txt, cut and paste here). It depends what the MKV contains.

[Cornucopia]

Problem with axioms like those are that they are too simplistic.

That's like "If I don't shoot you, you won't die."

Even the reverse isn't completely true (If I shoot you, you'll die), as there are clearly exceptions.

One main rule of thumb that you should follow is this:

If you have to recompress, you will lose some amount of quality.

The reverse to this would have been that if you don't recompress, you don't lose quality - THAT IS TRUE.

Now, the "SOME" amount can vary, depending upon many factors.

Another video rule of thumb that you can at least start using as a general guideline is this:

(Bitrate x Codec Efficiency) / (Resolution * Complexity) + Resolution = Quality

Now, this uses elements which are a little fuzzy, like "Efficiency", "Complexity" and "Quality". Sorry, can't get much more exact than that.
What you should know is that (for a given bitrate) MPEG2 is more efficient than MPEG1, MPEG4 (ASP) is more efficient than MPEG2, and MPEG4 h.264 is more efficient than MPEG4 (ASP). Complexity has to do with the scene: randomness, fast cuts/action, sharp contrasts, etc. Note that lowering resolution will in one way make the quality better because you have more bits per pixel, but will in another way make it worse because you have less visual clarity. It's often a trade-off.
Even with these "fuzzy" parameters, you can get a good idea of areas to tweak to get the "Quality" that you want.

Scott

[johns0]

If the mkv is within accepted blu-ray/avchd specs then it will not need to be re-encoded and only authored to avchd.

[mark63534]

I'm no longer going to hide the fact that I downloaded this from the net... but here's the MediaInfo.

General
Complete name : Clash of the Titans (2010) BDRip m-720p x264-McClassick.mkv
Format : Matroska
File size : 2.33 GiB
Duration : 1h 46mn
Overall bit rate : 3 141 Kbps
Encoded date : UTC 2010-07-15 23:35:24
Writing application : mkvmerge v3.0.0 ('Hang up your Hang-Ups') built on Dec 12 2009 15:20:35
Writing library : libebml v0.7.9 + libmatroska v0.8.1

Video
ID : 1
Format : AVC
Format/Info : Advanced Video Codec
Format profile : High@L4.1
Format settings, CABAC : Yes
Format settings, ReFrames : 5 frames
Muxing mode : Container profile=Unknown@4.1
Codec ID : V_MPEG4/ISO/AVC
Duration : 1h 46mn
Bit rate : 2 500 Kbps
Width : 1 280 pixels
Height : 528 pixels
Display aspect ratio : 2.40:1
Frame rate : 23.976 fps
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.154
Stream size : 1.81 GiB (78%)
Writing library : x264 core 77 r1292 e381f6d
Encoding settings : cabac=1 / ref=5 / deblock=1:-1:-1 / analyse=0x3:0x133 / me=umh / subme=10 / psy=1 / psy_rd=1.0:0.0 / mixed_ref=1 / me_range=16 / chroma_me=1 / trellis=2 / 8x8dct=1 / cqm=0 / deadzone=21,11 / chroma_qp_offset=-2 / threads=3 / nr=0 / decimate=0 / mbaff=0 / constrained_intra=0 / bframes=3 / b_pyramid=0 / b_adapt=2 / b_bias=0 / direct=3 / wpredb=1 / keyint=250 / keyint_min=25 / scenecut=40 / rc_lookahead=40 / rc=2pass / mbtree=1 / bitrate=2500 / ratetol=1.0 / qcomp=0.60 / qpmin=10 / qpmax=51 / qpstep=4 / cplxblur=20.0 / qblur=0.5 / vbv_maxrate=50000 / vbv_bufsize=50000 / ip_ratio=1.40 / aq=1:1.00
Language : English

Audio
ID : 2
Format : AC-3
Format/Info : Audio Coding 3
Mode extension : CM (complete main)
Codec ID : A_AC3
Duration : 1h 46mn
Bit rate mode : Constant
Bit rate : 640 Kbps
Channel(s) : 6 channels
Channel positions : Front: L C R, Side: L R, LFE
Sampling rate : 48.0 KHz
Stream size : 486 MiB (20%)
Language : English

Text
ID : 3
Format : UTF-8
Codec ID : S_TEXT/UTF8
Codec ID/Info : UTF-8 Plain Text
Language : English


Now according to other threads, AVCHD compliant material has to have a resolution of 1280x720 for this to work( 1440x1080, 1920x1080, 1280x720, 720x480/576 are also "compliant"). As you can see, it is not compliant as it is 528p.

What I understand to do now is add black bars using multiavchd and recode, but the thing is: If I reencode, even if I'm NOT re"compressing" it, is it still possible to lose some quality even though the bitrate would be higher than the source?

That puzzles me.

(The bitrate shown in multiavchd had a rough estimate of over 4000 kbps.)

[jagabo]

If I reencode, even if I'm NOT re"compressing" it, is it still possible to lose some quality even though the bitrate would be higher than the source?

Yes. Reencode=recompress. The process involves decompressing the source, adding borders, then recompressing. If you use enough bitrate the loss of quality will be minimal. Maybe not even noticeable.

Since you left the filename in your MediaInfo post, and admitted to downloading the file, you're thread will likely be locked.

[mark63534]

If I reencode, even if I'm NOT re"compressing" it, is it still possible to lose some quality even though the bitrate would be higher than the source?

Yes. Reencode=recompress. The process involves decompressing the source, adding borders, then recompressing. If you use enough bitrate the loss of quality will be minimal. Maybe not even noticeable.

Since you left the filename in your MediaInfo post, and admitted to downloading the file, you're thread will likely be locked.

I don't blame you for saying that. Could this result in a ban?....

[videopoo]

I'm no longer going to hide the fact that I downloaded this from the net...

Well...that ends this discussion

[jman98]

I'm no longer going to hide the fact that I downloaded this from the net...

Well...that ends this discussion

Yeah, you probably should have continued to hide that fact. All you had to do was change the title to something innocuous like "Throwdown with Bobby Flay" and no one would have paid any attention.

[johns0]

mark63534-Asking for help with illegally obtained movies is against form rules,this thread is closed.