High pitch sound when playing .mp2

[Zot]

Hi,

I'm using besweet (latest versions and settings as per the AC3 to MP2 guid). If I rip the audio from a DVD with DVD2AVI, the resulting WAV file sounds clean. If I convert the wav file to MP2 using besweet and the settings in your guide, the resulting MP2 file has a high pitched squeal running throughout the mp2 file (in the background but very noticeable on my PC and slighty noticeable from the TV when converted to SVCD with tmpgenc and played through my APEX 1500. (I use PowerDVD and Windows Media player) to playback on teh PC.

If I rip the AC3 audio directly from the VOB files using the *.lst file from smartripper and then use tmpgenc (2.53) to create an SVCD with the resulting MP2 file, I still get the squeal and the audio in the resulting mpg file starts getting ahead of the video so that by the end of a 2 hour movie, I could be a second or more off.

If I just import the DVD2AVI wav file to tmpgenc, I still get the squeal plus a tinny sound that I guess tmpgenc users have complained about before. Same squeal if I use 2lame as an external decoder to Tmpgenc.

It seems like anything I try to encode ends up with a slight but noticeable squeal. Has anybody seen this?

My system is a dual Athlon MP1800, Tyan S2466 Mboard with Win2K (SP2) and I'm using a Turtle Beach Santa Cruz sound card.

Thanks,

Zot

[DSPguru]

was FRC (ntsc 2 pal or similar) involved in the process ?

[Zot]

Sorry, I must claim ignorance (I'm sorta new at this). If FRC is another tool, no I'm not using it.

All my tmpgenc SVCD's are created in NTSC output, but I get the squeal before that. I can hear it in the MP2 that is output from besweet too. The only thing I get clean is the WAV file from DVD2AVI.

Thanks,

Zot

[DSPguru]

Originally posted by Zot
Sorry, I must claim ignorance (I'm sorta new at this). If FRC is another tool, no I'm not using it.never mind that..

Originally posted by Zot
Same squeal if I use 2lame as an external decoder to Tmpgenc.looks like you've got a very unique track in your hand. a signal that all mp2 encoders fail for.
could you uploda the ac3 someplace, so i can check it ?
could you tell us what's the DVD you're trying to transcode ?
could you paste here the commandline you used with BeSweet ?

[Zot]

Thanks - When I get home tonight I'll post the command line as well as upload the AC3 file somewhere. It's 1:50 on the west coast, so it will be about 8:00 PM PST tonight before I can get the particulars.

Thanks!

Zot

PS - forgot to mention, this is happening to ALL my rips:

Anna and the King
Along Came a Spider
Atlantis

[Zot]

Just an update:

I discovered every MP2 I play - whether I create it or download it - has this high frequency hum in the background. I've tried many combination of commands with besweet (for example

"g:\dvdpack\Azid\BeSweet.exe" -core( -input "f:\Othello\othd2a AC3 T01 2_0ch 192Kbps DELAY -83ms.ac3" -output "f:\Othello\othello_besweet.mp2" -logfile "G:\dvdpack\Azid\BeSweet.log" ) -ota( -d -83 ) -azid( -z1 -b1 -s surround -c normal -g max -L -3db ) -ssrc( --rate 44100 ) -2lame( -m j -b 224 )

, tmpgenc and bbmpeg - wav and MP3 files I make don't have the dynamic range (or hum), mp2 files have it. It doesn't matter what computer I create them on listen to them on. Must be something inherent with MP2. Granted, it is only obvious with a quite passage, but it is there none the less (kind of like the hum of a hard drive on laptop - you notice it, but you get used to it). Is this just a fact to live with, with MP2? Or do 'commercial' encoders eliminate this? Or are my ears just being too picky :-)

I was going to upload snippets of the audio clips to usenet for feedback, but now i'm thinking this is just inherent to MP2 ( just like the occasional blocking or artifact with TMPGenc, no matter how high the bit rate).

Being a newbie, I may have my expectations too high, but I'm willing to adjust them!

[DSPguru]

hehehe, sounds like you got great ears :).
anyway, toolame is considered to be the best mp2 encoder, so if you hear that squeal with toolame encodes. i guess it's a built-in problem.

btw,
if you have such a wonderful hearing skills, will you compare the sound quality of mp2 created by BeSweet v1.2 comparing to v1.11 ?
i would love to get feedbacks from you !

[MaTTeR]

Some SoundBlasters use to have this problem on Windows2000 but I'm not sure what fixed the issue or if it was ever addressed by Creative. Make sure your SB drivers are up to date.

[tenebrenz]

This sounds like it could be the PowerDVD audio direct-show filter, I remember it had a bug in it a while ago when dealing with some MP2 streams. If I played the MP2 in winamp it played fine.

[DSPguru]

tenebrenz is right.

you told as alot about how you tried to encode, but didn't tell us how you decode ;).

[Zot]

1. I rip with Smartripper.
2. DVD2AVI, demuxing all audio tracks.
3. Use Besweet GUI following the recommended settings found elsewhere on this site to convert the AC3 file to MP2.
4. use TMPGENC 2.53 to encode mpeg-2 with the besweet MP2 for audio input
5. De-mux with TMPGENC
6. Use avi2mpeg2 to resynch and split
7. Use VCDEasy GUI to create and burn SVCD's.

If I do this, the squeal is unacceptable when using PowerDVD, and pretty annoying when listening through my standalone Apex player.

If I don't do auto gain or dynamic compression and If I use the besweet output MP2 as the audio input to avi2mpeg2, the resulting SVCD sounds pretty good.

If I do use auto gain and/or dynamic compression but still use the MP2 to input to avi2mpge2, the audio range is better and the background noise isn't noticeable on my Apex DVD player (can still hear with PowerDVD, but it is tolerable).

So, looks like I have a solution. However, I'm curious if anybody elses notices this? Take any move that starts with the 20th Century Fox lead in and listen to it as a wav and/or AC3 from DVD2AVI, and then MP2 output from Besweet with auto gain and dynamic compression turn on. Turn the volume up as loud as you can stand and you will hear the background 'squeal' (sometimes even before the drum roll begins) or as it transitions from the 20th century audio clip to the movie soundtrack.

If nobody else can detect this, I'll eat this posting :-)

Thanks,

Zot

[DarkAvenger]

Could you try to decode that mp2 to wav and make a frequency analysis of a part where you *only* hear that sound? When I tried to encode a ac3 with gain of -100db and amplified it later by 100db (32bit) I heard a bad high pitched sound in there beside the actual audio. It is probably not a problem of BeSweet, as I tested with HeadAC3he, but I thought it was only mp2enc producing this and I thought is was below the level 16bit WAV could represent. But when you say toolame is also doing this, is bad. (Maybe a bug in dist10 code, on which both encoders are based on?) Have you tried encoding to mp2 with QMedia?

[Zot]

OK - any suggestions for a frequency analyzer?

Zot

[DarkAvenger]

eg. part of Cool Edit

[HockeyStick]

It's my third thread discussing that issue and nobody seems to came with an answer. Here's my BIG problem: The audio conversion from AC3 to MP2 deliver an anoying jerky hiss in the background, mostly heard in high-pitch sound and in calm scenes. I made some tests: AC3 to WAV (with azid) is perfect(playback with WinAmp). The WAV file to MP3 (with Lame) is again PERFECT. BUT, The same WAV to MP2 always came out with the same result, no matter the settings. I've try BeSweet(toolame), the internal mp2 encoder in TMPGenc(really sucks!), Qmedia, ReMPEG, Wav2mp, etc...
I'm new to svcd, but not from audio encoding. And i can distinguish good sound from bad. At first, i tought it was my settings. I followed every guide possible, but nothing to get rid of it...
Is there someone who experience or notice that problem???
Since the MP3 conversion gave me very good results, it's almost certain that the problem lies in the MP2 encoder programs.

[DarkAvenger]

How did you listen to/decode the mp2?

[MaTTeR]

Nice subject line...very meaningful HockeyStick.

While I understand your frustration, please stick to the forum rules as per descriptive subject lines.

[HockeyStick]

I play the movie with WinDVD on pc and my standalone pioneer dv-343. To be sure, i've rip a chapter of my movie and made the test conversions (ac3--wav--mp2 and even mp3) and play those files with WinAmp. Both Wav & MP3 came out just fine, but not mp2!!!
The problem is more evident with headphones, it's like the kind of hissing of a low bitrate encoded mp3, but not that evident when the sound gets loud in the movie, but still there.

[DJ Bobo]

@ Hockeystick
I remember having answered in another topic of you that I also have the same "problem". It seems to be normal.
I hear this hissing only after multiplexing though.

[HockeyStick]

Back again...
To be sure, i ran another test...(my first was with Gladiator)
I've ripped the first chapter of Titanic(ntsc), and convert the ac3 to wav with Azid. Then, i've convert it to MP3 and MP2 to compare. The first minute of the movie is a good exemple of the problem. The WAV came alright, so was the MP3. But, again, the MP2 was not. You can clearly hear the squealing when the voice is singing in that first minute.
If someone experience the same problem, and get ride of it, it will be a big relief...
Thanks in advance,
HockeyStick

[LigH]

Just a few simple thoughts:

* Is it possible that this noise is a result of a bad playback (e.g. does in only appear when listening with WinAMP, do other players - e.g. Sonique, MADplay - play it differently)?

* Is it possible that the reason is a too low bitrate (192 kbps shall be the least for MP2)?

[HockeyStick]

Hi LigH,
Yep, i've try to play those files through WinAmp, MusicMatch, Sonique, WMP and MADplay. All the same results. I've encode the mp2 at 224 kbps and even tried 320 kbps!!!
I don't know if there's a way (settings) to attenuate or filter the high-pitched section of the sound when encoding in mp2??? Maybe it can resolve the problem.

[ChristianHJW]

Just to be sure, you are downsampling to 44.1 KHz with ssrc.dll, right ? Note that all existing MP2 encoders will encode 48 KHz , but are not optimized for that .... same may apply to decoders ...

[HockeyStick]

Yes, i've try both: downsampling to 44.1 khz(ssrc.dll) and stay with 48 khz. Another good track to test, was chapter 27 of Gladiator. If anybody have that DVD, try it. Convert the ac3 to wav, mp3 and mp2. And compare. In the first minute of that track, when Lisa Girrard is singing, you can clearly see the difference.
I know, compressing a file should result on a lower quality, but since the mp3 file came out perfect(it's more compress!!!), i'm questionning the quality of mp2 encoders, or MP2 itself.

[Gabriel_Bouvigne]

I have an idea. First perhaps the "mp3" in general might not be so good. You tried with Lame, but perhaps with another encoder it might be different.

Potential explanation about your problem. Usually ac3 tracks have an high dynamic range but only a very little part is using the higher part of the dynamic range. So if you decode ac3 to 16bits wav, it means that most of your track will be a low volume.

Now, encoders are using something called Absolute Threshold of Hearing (ath). And for this ath, they need to set a level. Usually they assume that the lowest point of the ath curve is at 96dB under the max value of your input file. But in your case, the max value of your input track once encoded in 16bits is perhaps something like 60dB. It's very likely that only a minimal part (like 1-2 ms) is a 96dB. So if the encoder is using a fixed level ath, then you just lost 36dB of signal/noise ratio.
Lame doesn't do this exactly in this way: it's able to adjust the ath level according to the peak value of the track.

In order to test if this is your problem, you should try to do a dynamic compression on your track and then encode to mp2. If things are improving, then your problem comes from there.


Btw: would it be possible for a moderator to change the topic of this thread to something less "aggressive" and more meanginfull?

[DSPguru]

Originally posted by Gabriel_Bouvigne
would it be possible for a moderator to change the topic of this thread to something less "aggressive" and more meanginfull? done :).

[HockeyStick]

Thanks Gabriel for your excellent technical explanation,
I'll give it a try. And sorry for the "agressive" topic, but i was exasperate by the fact that it's been two weeks now that a search for an answer.
By the way, i came close to excellent sound but at 384kbps :D
Thanks for your help,
I'll post my results.
regards,
HockeyStick

[HockeyStick]

After a few tests, i've got pretty good sound...at 384 kbps!
The dynamic compression help maybe a little, but not enough to get rid of the hissing. Since my standalone dvd can playback at 48Khz and at 384kbps i will stick with those settings until i find a way to get good sound at 224kbps.
Just another question: It seems that DVD2SVCD can't handle audio at 384kbps! The chapter i've test came out with no sound or very choppy one. But when i do all the steps by myself it was different: when i used BeSweetGui to convert the AC3 to WAV first and then convert it to MP2 (not AC3 to MP2 directly), it gaves me excellent results.
Hummm...

[HockeyStick]

After multiple tries, i've came up with pretty good results at 224kbps. Here's what i've done for the audio:
1- DVD2AVI to get the .d2v file and the .ac3 files.
2- GraphEdit to convert the AC3 to WAV
3- TooLame (using TooLame Gui and NOT BeSweet) to convert the WAV to MP2.(settings: -m s -b 224 -e)
Curiously, the .wav files generated by AZID and GraphEdit seems identical when played in WinAmp for testing purpose. But, when converted in .mp2, the one from GraphEdit gaves me better results...way better!!! The squealing noise in high-pitch sound was almost gone.
I don't know excactly how the sound is process in BeSweet, but i can tell you that the resulting quality is not that good...unfortunately for DVD2SVCD.

HStick

[Antimon]

Why convert to wav t begin with.......

Besweet c an convert ac3 into mp2....i dont see the purpose of wastign time transcoding to wav if you dont have to

[HockeyStick]

-Antimon

To answer your question...i don't know why, but it seems that the quality of the .mp2 is not as good when you convert the .ac3 to .mp2 directly with BeSweet (HISSING...if you read the posts...)!!! That's why...and if you want to test, listen carefully with headphones and you will notice those artifacts. Try ripping a chapter for testing purpose (i was using Gladiator chapter 27), and give me some feedbacks...
BTW, i know the problem is more evident when the sound is converted with TMPGenc, BeSweet do a better job...but not like a want. And by converting the AC3 to WAV with GRAPHEDIT and then convert that WAV to MP2 with TooLame gave me very good results if i compare with
AC3--»WAV--»MP2 or AC3--»MP2 directly with BeSweet! I repeat, the process to convert AC3 to MP3 (for Divx) in BeSweet is perfect...but not MP2 (SVCD)! I don't know why...

HStick

[Antimon]

I'll test with the chapter in titanic

it just strieks me as odd that you'd gtet hissing they use the dsame libraries...

fi you convert from ac3 to wav in besweet is the hissing in the wav?

I did read theposts,
graphedit is a pain :-)

but if ythe hissig is in the way then you knwo the problem lies with the settings in ssrc or mpglib

if the wav is fien you knwo it lies in toolame

[Antimon]

I tell ya man, i'm not hearing it , the onyl way i get any noise floor hissign at all is if i amplify it with eq pretty heavily, otherwise it's very clean

my command line
"C:\BEsweet\BeSweet.exe" -core( -input "c:\Temp\vts_01_([0x81]_Audio_English_AC3(6Ch)_48kHz___)_Delay_-227ms.ac3" -output "C:\PLANET_OF_THE_APES\test.mp2" ) -azid( -z1 -b1 -s surround -g max -L 0db ) -ssrc( --rate 44100 --twopass ) -2lame( -s 44.1 -m s -b 224 )

[HockeyStick]

-Antimon

Thanks for trying to help me, i appreciate.

I know it's seem strange...but i can tell you that i can clearly hear the squealing artifacts in the sound, especially when it's calm and there's a high-pitch sound (like the voice singing at the beginning of Titanic or the one (Lisa Girrard) in chapter 27 in Gladiator). It's the same kind of artifact in a low encoded .mp3 (<=128). It's not the hissing normaly heard in background.
In BeSweet, i repeat, all WAV files came out clear. WAV to MP3 was clear too(192kbps). WAV to MP2--->squealing (settings: -m s -b 224
-e). I've tried SSRC 48-->44.1; i tried keeping it at 48khz too; i tried all the PSY settings, etc... and the only way to get good MP2 sound was at 384kbps!!!
I don't know why, but i just found that by using GRAPHEDIT and TooLame the sound(at 224kbps) was much better than with BeSweet...
Can it be hardware problem? Or codec problem? Bad .dll? I'll try to reinstall all those softwares...
I'm using: PIII 1Ghz; Asus TUSL2-C; 256 Mb; Soundblaster pci-128; Western Digital 40Gig 7200 ATA100; Windows 98SE.

HStick

[Antimon]

Well if the wav generated si clean then atleast we narrowed it down to the toolame dll, what version is besweet using compared to the version you're using stand alone, maybe one is newer.

[dani82]

here's what i do to make a mp2, first i convert the ac3 to wav using px3con, then a couple of sound edits (not really important), then convert the wav to mp2 using MpegDj Encoder, this always works for me, no audio problems or anything, except the program is a demo of some kind; either cd ripping or wav encoding; oh well, there is keygen somehere on the net.

[Bill_st]

Whenever I play an .mp2 file (no matter what encoder I use) on WMP 8, PowerDVD 4 XP or import them into Sound Forge 5.0, there is a very annoying high pitch sound not present in the source files, represented as thin lines in a spectrum analysis at fixed frequencies.

I can play those same .mp2 perfectly on Winamp, so I guess it must be cyberlink's DSF that must have some bug with .mp2 files (plays other file types well though). Is there any workaround for this? (beside deinstalling PowerDVD).

Also, I have very little knowledge about DirectShow filters, so I would appreciate a link to some concise guide about how to use them, and which are preferred for each task..

[DSPguru]

i believe all noise reports are caused by usage of joint-stereo in mp2 encoding.
use stereo!

[HockeyStick]

I can tell you, the artifacts are there even with stereo mode. BTW, i'm getting better results with BeSweet 1.4RC8. Previously, i've install the newest version of WinDVD (v.4), maybe it has install better DS filters??? Artifacts are almost gone at 320 kbps!!! But it will be nice to get perfect sound at 224 ...

[DSPguru]

Originally posted by HockeyStick
I can tell you, the artifacts are there even with stereo mode. BTW, i'm getting better results with BeSweet 1.4RC8. Previously, i've install the newest version of WinDVD (v.4), maybe it has install better DS filters??? Artifacts are almost gone at 320 kbps!!! But it will be nice to get perfect sound at 224 ... is there any difference in quality when you encode at 44.1khz comparing to 48khz ?

[HockeyStick]

I've made some tests with an AC3 file (rip from a DVD chapter), and yes there's a tiny difference in quality between 44.1 and 48khz...in favor of 44.1!!!(at my surprise). But so tiny that i don't think it's worth the extra encoding time...and the "famous" artifacts are still present at 224 kbps... i still think it's inherent of MP2.

My usual settings in BeSweet are:

-azid( -s stereo -L -3db --maximize ) -ota( -d -343 ) -ssrc( --rate 44100 ) -2lame( -m s -b 224 -e )

[DSPguru]

Originally posted by HockeyStick
the "famous" artifacts are still present at 224 kbps... i still think it's inherent of MP2. i doubt that it's inherent in MP2, but i do believe it's inherent in dist10. (fraunhufer's original reference encoder code, which almost all mp2 encoders are based on).

[HockeyStick]

Just for testing purpose, is there an mp2 encoder who is base on something else than dist10 code?

Thanks for helping

[DSPguru]

i bet there is, but i don't know of any.

[stl]

I've tried HeadAC3e and Toolame and both produce MP2's that have this annoying high pitched buzzing in the background.

Is this normal, am I doing/not doing something, can this be fixed?

[Wakeboardsam]

I'm as newbie as they come and just got into this converting in the last couple of weeks, but... i had hissing at high notes like you guys have described and i was playing with the settings and found that in the encoding tab in the dvd2svcd program and i changed the audio from vbr to cbr. i'm not sure if that had anything to do with the hissing but on all my videos i have done from then on there is absolutely no hissing at all. niether at high notes or just in quiet scenes. i hope this helps. Sam

[BGane]

It has been several months since a post has been made on this thread, but I have been observing the same problem with many of my files. Originally, I thought that the problem was on the encoding side, but my work in the past days leads me to believe that the bug is on the decoding side.

When you play an MPEG file (of any description) on your PC, through any of the DirectX compliant players, the Microsoft infrastructure (ie. DirectShow) sends the audio stream through the Microsoft MPEG Audio Decoder. The decoder then hands the decoded stream to the indicated DirectSound device.

Now, you can replace the standard Microsoft decoder by registering another decoder on top (eg. Moonlight Elecard Odio Dekoda). The decoder is in a file called "mlcom.ax", and is available for 21 day trial on Moonlight's site.

Another approach that I experimented with, is to convert the MPEG file back to a WAV, using Goldwave - which can read my MPEG1 audio/video file directly, stripping out only the interleaved audio and producing a WAV.

I found that when I replaced the Microsoft decoder with Odio Dekoda, there was a significant drop (and my ears aren't super sensitive!) in the high-pitched squeal. Unfortunately, the Odio Dekoda decoder isn't perfect - there was still some notable "pumping" hiss that I could hear. So - it was BETTER, but not perfect.

Of further note, when I listened to the WAV file generated by Goldwave - there was NO high pitched squeal. Now - when playing back a WAV, the MPEG decoder is completely bypassed, so that would make sense, if the bug is in the MPEG decoder process.

Incidentally - spectral analysis of my encoded file shows no artifacts at 12-14khz, where I estimate the high-pitched squeal to be. This further supports my belief that the squeal is, in fact, not present in the file, but is generated somewhere in the decoding process.

My conclusion: There is a bug in the standard Microsoft DirectShow MPEG decoding filter process which is generating these artifacts on playback.

This leads me to a question: What DVD players are people using? I have noticed that the PowerDVD audio decoder isn't much better than Windows Media Player 9, but perhaps Cyberlink borrowed code from Microsoft? I would be curious to know if anyone is experiencing the same problem and would be using either a Mediamatics DVD player or an Intervideo DVD player (ie. WinDVD)? These other players may have better MPEG audio decoders that are being registered over the Microsoft default filter.

The trick seems to be in determining which MPEG audio decoders are doing a good job, and which ones seem to be the source of the problem.

[stl]

Wow, thanks for all the info.

So it seems like there is no real cure for this problem.
What I've been doing is using the AC3 encoder that is bundled with Scenarist to convert the MPEG file to an AC3. This completely eliminates any high pitched whine and AC3 is a much higher quality format in any case. Yes, I know, it is not an inexpensive solution.

[BGane]

So - because you have converted the file to something else - you are bypassing the poor Microsoft decoder, and eliminating the problem.

All I would like to do is find a decent MPEG audio codec, that I can register as a DirectShow filter. That will solve the problem. But finding one has proven difficult for me!

[BGane]

I found one. I'm now using the Ligos MPEG Audio Decoder.

It took me a while to figure out how to get it to be the default decoder selected for apps like Media Player. You need to change the "Merit" value to be higher than that of the Microsoft decoder, then Media Player will pick up the Ligos decoder instead.

So the problem is solved for me, but you have to use another decoder if you are having this problem.

Perhaps changing how you ENCODE will allow you to step around the problem, but that is basically implementing a work-around. The issue is with the Microsoft MPEG Audio Decoder. Microsoft really should take a look at this! Or perhaps it is Mediamatics who are at fault - as Microsoft licenses the decoder from them.