Playback issues - 256KBit MP3

[svenc]

Hi gonemad.
I have some trouble with 256 KBit MP3 files.
With archos mediaplayer, there are no problems - the replaying is without any gaps or noises / distortions (it's clear in replaying).
When I use your player, I have issues such distortion / flutter etc. in several files. I cannot describe this problem exactly, but it seems the mp3 decoder has problems with different files (encoded with mp3 codec from Adobe Audition C6).
I cannot fix it with the internal EQ / limiter; in background there is kind of flutter or a noise or a kind of distortion.
Can I upload a test-file (filesize ~340 MB)? PN?
You will hear a distortion or so on left channel with your player, but not with winamp on PC or with archos mediaplayer....
In my mind, the 3rd party decoder is the trouble maker.

[GoneMAD]

Email some of the files to [e-mail]

The archos 5 honestly is pretty bad so if its a performance issue there really isnt much more that can be done. Ive spent weeks optimizing for that device.

[svenc]

Okay. It seems you are right. The same test file on my 8" archos tablet is working fine, without any noises etc. As workaround, I will test on archos 5 with 192 KBit test file. The funny thing is, other 256 KBit files are working fine on my archos 5 with your player. Mmh, when 192 KBit is not working for me I will try with LAME encoder.

[svenc]

Mmmh.
Few days ago I re-encoded one of the "problem" file via another encoder to 192 KHz.
So. The old MP3 is still working without any problems on my Archos G9 80 (gonemad player and archos media player) and with the archos mediaplayer on my Archos 5IT. The new one is still working on my G9 80 and 5IT (same way).
In each case (old and new one) I cannot replay the files on the 5IT with gonemad player without problems. Before I upload a test file, a question to you.

Do you use another decoder or is there another decoder implemented on the 8" tablet as on the 5IT?
On the 8" tablet, I use Android 4.0.4. On my 5 IT, I use Android 1.6.
In one of your last comments you wrote that you are using an external decoder because of licence problems (or so). I have no information, which decoder you are using under Android 4.0.4 and under 1.6. It's very confusing, because the "problem file" ist working without any problems on my 8" tablet with 4.0.4 and your player.

It could be that the mastering of the files is the trouble maker, because I use bass and sub bass EQ in the mastering process. Maybe your internal EQ cannot handle this kind of files (or anything other, because there are no problems on my 8" tablet). A decreasing of a band does not fix the issue.

How large can be a file that I send to you?

[GoneMAD]

4.0+ has 2 decoders. OpenSL and then will use the mp3 decoder library found on the device if its there. OpenSL is a library google officially supports (bug its buggy). Up until a few versions ago the OpenSL decoder was on by default for 4.0+ but i turned it off by default recently because it was causing too many issues.

Prefs -> Audio -> Playback -> Enable OpenSL

If you use something like mediafire or dropbox you can send as large of a file you want. Unfortunately if the issue is just playback is distorted or choppy, there is nothing I can do. I do not have any of the source code for the mp3 decoders. If playback is playing at the wrong speed (slower or faster).. that is something i can address since its not an issue with the decoder but how the decoded audio is being played back.

As for the equalizer, i've had a few cases where very low quality audio files (we are talking 8-16khz sample rate and low bitrate) will get butchered when adjusting the high frequency bands. I do not know exactly why but most likely its due to the low quality files having the higher frequencies cut out during compression which causes issues with the equalizer

[svenc]

Thank you for the anwser. I have no idea about the reason, but I re-mastered those files with extra bass. The funny thing is, there is no problem with the archos mediaplayer (DSP replay?) and on the 8" tablet, there is no issue with archos media player AND your player.
Maybe the EQ of the gonemad player cannot process this kind of "distortion" on my 5 IT. I will upload a test file to a OCH during next days and will inform you about PM about the link.
Normally you will hear distortions on left channel.... Next problem. Do you have a similar player like an Archos with Android 1.6 or another old device with slower CPU? Maybe an actual device is fast enough to decode this files and you will not hear the distortion...

[GoneMAD]

i have the 5IT still, so yea if you can get me the file somehow I can give it a listen

[svenc]

Sorry for delay. Okay. I will testing again. Remember - fully HDD, hence EQ problems. After this, I re-installed your player again and until now, I have not tested again. Hope, the problems still fixed.

[svenc]

So. The playback is the same as before. After detailled analysing it seems to be a kind of sub bass clipping. I will re-master the original file, because I re-mastered an old radio session. There is too much treble and too much bass in the mastering-job. Maybe the device is overloaded to prevent this kind of clipping (a lower EQ gain and Limiter ON does not solve that problem).

[GoneMAD]

unfortunately there is nothing i can do. When running anything through a DSP you risk distorting the audio. There are many different dsp filter algorithms that can be used to make an equalizer and i guess whatever the archos eq is using doesnt suffer the same faults as the GMMP eq (you should try turning it to high quality to see if that is any different.. that is a different filter compared to the normal quality)

Im not a digital signal processing expert so unless improvements are made to the dsp library im using.. there is not much i can do

There was one other case on the archos 5IT where the eq would really mess up the sound.. i twas on some very low sample rate / low bitrate file that would emit a high pitch squeal if you would increase the higher eq bands. This only happened on that device and i couldnt reproduce it anywhere else

[svenc]

I don't know, only these files are making trouble. And only these files are mastered with many sub bass - in my mind too much for this device.
Sorry for involving. During next weeks, I have a little bit more time to re-mastering the files (with less sub bass). Hope to solve this problem definitively.

[svenc]

After months of searching.... there is a solved problem...

The "issue-files" were files from DAT-recording. 48KHz / 32Bit. The audio software does not change the sample rate automatically while creating a MP3-file. It seems, my Archos 5 IT was not able to play these files without distortions.
After re-sampling to 44,1 KHz / 16 Bit all files are working fine.