Converting HDTV recordings to MKV - quality issues

[Bully9]

Recently I've been trying to rencode High Definition .ts files recorded from the TV to x264 mkv using megui. The method i've used is to produce a dga file and a simple avs script - typically something like

LoadPlugin("C:\Program Files\MeGUI\tools\dgavcindex\DGAVCDecode.dll")
AVCSource("F:\Video.dga")
#deinterlace
#crop
LanczosResize(1280,720) # Lanczos (Sharp)
#denoise

I've then used the x264 codec in megui - automated two pass, using default values - and all seems to go as it should.

But the result is a flawed mkv video with a kind of occassional pixillation - especially around the edges of objects.

I've done literally hundreds of SD Xvid transcodings over the years with no problems, but can't seem to get this type of conversion to work - it's very frustrating and i have absolutely no idea what the problem might be.

Any help appreciated, thanks.

[Baldrick]

I would first try another x264 frontend and see how it looks like, like handbrake, staxrip, xvid4psp, xmedia recode.

If still same issues it might be because of the source.

[Bully9]

Hello Baldrick. The source does play fine. Could that still be the problem? In what way?

[poisondeathray]

If your source was interlaced, the pixellation is a known and well documented issue with dgavcindex and some PAFF (interlaced) streams

Use another source filter

e.g. DirectShowSource + ffdshow

If your source was interlaced, you should deinterlace before resizing

[Bully9]

Dohhh! I used to use direct show for many years but switched to solve other issues that i don't recall right now. Oh well, i'm grateful for the tip as mediainfo reports the source is interlaced. I don't suppose a different front end will make a difference if it's a dgavcindex/interlacing problem.

[poisondeathray]

Well mediainfo can be wrong (it just reads the header) , just like the autodetection schemes of all the front end GUI's can make errors as well

You can just make changes in the script manually. Some might use a different source filter for 1st choice, not sure

I don't know about UK broadcast, but in NA, if it's 1920x1080 it will always be broadcast as 60i (even if it's telecined 24p in 60i). I suspect in the UK it will be broadcast as 50i . Since you were resizing in your script to 1280x720, I assumed you were using a 1920x1080 source

And yes, Directshow has many problems as well, but for a straight encode it should work if your directshow filters/system is in order

[Bully9]

Source is actually 1440 x 1080 25fps and i know it's broadcast at 1080i. I have tried to resize to 1920x1080 with the same result. I wish i were more au fait with avisynth commands but i'll experiment and see what happens. I've tried staxrip and it gives the same result and i can't get to grips with its x264 gui to i guess it's back to megui.

[poisondeathray]

It you want to post a sample, someone will have a look at it and make suggestions

Chance are you won't get an ideal result with these auto script tools

If it is interlaced, you can't do a straight resize (or else you get a big mess). You can bob-deinterlace and reinterlace it later, if that's your goal. If your goal is progressive, you can leave it deinterlaced

[Bully9]

Ok, now i'm totally lost

How would i post a sample?

[poisondeathray]

you could cut a section of the original capture with tsmuxer or ts sniper

an ideal section would have horizontal panning, and if possible, a section where you said artifacts were visible on the encoded version

if it's <30MB, you can upload it directly here. If larger, you can use a free hosting site e.g. mediafire.com, sendspace.com

Also what is your end goal? PC playback, blu-ray ? etc... that might effect what decisions you make for deinterlacing (if applicable)

And what did staxrip use, that caused the same issues? Can you look at the log file? Did it use DGAVCIndex, or some other source filter

[Bully9]

I've made a small clip - about 9mb. How do i upload it there?

[poisondeathray]

there is an "upload files/manage attachments" button at the bottom of the reply box

[Bully9]

I'm aiming for an mkv to play on the TV via a HD media player. I used DGAVCIndex with staxrip - same as i'd used with megui.

[poisondeathray]

This stream sample is interesting, there appears to be decoding errors, with ffdshow (ffmpeg) , and coreavc , and mpchc decoder

It might be from the way you cut the file (e.g. if you don't cut on GOP boundaries). Can you repeat cutting a section with DGSplit ?

http://forum.doom9.org/archive/index.php/t-143963.html

What software did you use to play it, where there were no errors? Can you play that exact sample clip without errors?

[Bully9]

I'm trying to upload another clip but it keeps telling me my token has expired whatever that means. I'll keep trying, but the clip i managed to upload played fine in MPclassic and OK in VLC after a brief stutter.

[Bully9]

'Chunk' of more or less the same bit from dgsplit. Plays after a second or two black screen in VLC Won't play at all in MPclassic

[poisondeathray]

what directshow splitter and decoder are you using for MPC?

I can't find a decoder that decodes that 1st stream error free - which means whatever you encode will also contain those errors

The 2nd one plays fine, and decodes fine (if you use haali media splitter and ffdshow), which suggests the 1st example was cut improperly

If you don't know what decoder your directshow system has as default, render one of the videos in graphstudio and read where the pins connect to the decoder

[Bully9]

what directshow splitter and decoder are you using for MPC?

I have no idea

I've opened graphstudio but if i try to drop in dgsplit.ts it cannot open the file.

If i drop in New Sniper Project.ts, it shows this


Does that answer your question(s)?

[poisondeathray]

yes it does, the 2nd box "ffdshow video decoder" is your directshow decoder

I suspect if you updated your haali media splitter to the newest version , that you could open the 2nd sample. It decodes with a different size (there are black borders), because dgsplit cuts raw files (the files are actually encoded to mod 16, so 1440x1088 , not 1440x1080)

Anyways, I suspect you should be fine with using directshowsource on the uncut, original video

e.g.

DirectShowSource("video.ts")
LanczosResize(1280,720)

copy & paste that in notepad in the same directory as your video (fix the video name), and save it, then rename the file extension .avs

You can preview your script in vdub, or avsp for example, and see if there are any block decoding errors. Make sure you only preview linearly (e.g. with arrow key held down) . Do not scrub back & forth - this is where directshow will get you & cause problems

You can also do a mini-test, e.g. encode 1000frames to see if it looks ok. Just add Trim(0,999) to the end of the script

[Bully9]

Well, i understand about a third of what you've written. I'll give that simple script a go in megui. No need to deinterlace, then?

[poisondeathray]

I think the content is progressive, but it's flagged as interlaced. In my setup (with haali and ffdshow (or coreavc)), it's decoded as progressive 25fps, so no need to deinterlace. The problem with directshow is that it's inconsistent, and may be different between 2 different systems (even though the filters appear to be the same). You have to test it out with your configuration to be sure.

If you want a mini-test, just encode 1000 frames and check it out, before wasting time on a big encode to later find out something is wrong

[Bully9]

But if the channel broadcasts at 1080i, how could the video i captured not be interlaced?

[poisondeathray]

25p in 50i . It's just wrapped in an interlaced signal to make it standards compliant for broadcast, the actual content is progressive

In NA, the analogous stream would be a 30p in 60i stream

If it was truly interlaced content, you would have separate fields, each a different moment in time.

Another hint that it's progressive content, is you should see combing artifacts (horizontal lines), especially with motion, if it was interlaced.

If want a procedure to figure out what the content is (you have to change it a bit, e.g. different source filter, but the procedure is the same):

http://neuron2.net/faq.html#analysis

[Bully9]

I knew i shouldn't have asked!

Using the script from the neuron link in vdub, specifically

DirectShowSource("Video.ts")
AssumeTFF() # or AssumeBFF(). See the next FAQ.
SeparateFields()

it certainly looks as if the video is not interlaced. Although there is some slight combing in places.

I'm currently trying out the script you posted in megui. I'm doing the whole file because it seems to me every time i do anything to it i introduce other factors that may affect it, depending on what app/method i use. I'll let you know how i get on. Thanks for your patience.

[Bully9]

Well, using directshow seems to have cured the pixillation problem, so many thanks for that pdr

There seems to be a less well documented issue with dgavcindex and some progressive streams too!