mp4 bandwidth spikes cause stutter

[rmbolger]

Background:

Using Shark007 3.5.7 32bit and 64bit on Win7 x64. I've been ripping my DVDs to MP4 with Handbrake 0.9.6 using the "High Profile" preset. The files are hosted on a Windows 2008 R2 based home server accessed over SMBv2 via 5Ghz Wireless-N with plenty of signal strength. Shark is installed and configured as per the Setup and Usage page leaving everything in the Suggested settings mode.

I should also note that I know this problem is not specific to Shark. It happens even when Shark has been completely uninstalled. I just figured this community might be able to help me diagnose my problem.

The Problem:

When MP4 files are playing, every few seconds there's a bandwidth spike that causes the video/audio to stutter. The stutter really isn't enough to make the video unwatchable, but it's definitely annoying. Here's how the bandwidth spikes look in the Networking tab of Task Manager:


Attempted Fixes:

I've tried all the mp4 specific troubleshooting steps from the Setup and Usage page.

• [Reset All] and Disable LAV Audio: No Change
• Switched to Haali and Gabest splitters on the MPG~MP4 tab: No Change
• Disabling the Microsoft Video Decoder on the SWAP tab DOES FIX the problem. However, it has two unfortunate side effects. 1) AVI(Xvid/MP3) audio playback breaks in 64bit WMP and MCE, 2) Audio volume on MP4 playback is very low.
  

Playing back the file in an alternative player like VLC also fixes the problem. The bandwidth usage stays steady in the 1-3% range.

Personal Analysis and Other Tests:

Clearly this has something to do with the Microsoft Video Decoder.

Overall file size (or video length) seems to matter. I did some tests encoding short (2 min) clips from the same source with the same settings in Handbrake. But they don't cause the bandwidth spikes like the full length files do. I don't know where the tipping point is because I haven't had a chance to make enough clips increasing in file size to find it.

The problem is not restricted to a single system or wireless NIC. My main HTPC is an i3 based Asrock Vision 3D with a Linksys WUSB600Nv2 wireless NIC. My laptop is an i7 based Dell M6600 with an Intel Ultimate-N 6300 AGN wireless NIC. Both of these (and other systems in the house) exhibit the problem.

The bandwidth spikes also occur over gigabit wired links as well. But it doesn't actually cause stuttering in those circumstances. I think the reason is that the spikes are smaller relative to the overall bandwidth. The spikes on wireless are roughly 35% of a 300Mbps connection whereas they are only about 5% of the 1Gbps connection.

*Edit:* Putting the same encode into an MKV container does fix the problem. But I don't really want to tweak the container on all my existing files as I also use them on devices that don't support MKVs (and can't use on-the-fly transcoded streams).

Barring an actual explanation or fix for why the bandwidth spikes are happening in the first place, I see myself with a couple options:

• Run a gigabit hard line to the HTPC so the spikes don't affect playback anymore. This is ultimately what I've planned to do anyway. But I'm still hoping to shed some light on the underlying problem.
• Disable the Microsoft Video Decoder, but only for MP4 files. Theoretcially, this would leave the AVI files still playable and I'd just have to deal with lower volume on MP4s. The problem is that I haven't been able to figure out how to actually do this within the Shark Settings applications.
  

[Shark007]

(03-17-2012 04:31 PM)rmbolger Wrote:  [*]Disabling the Microsoft Video Decoder on the SWAP tab DOES FIX the problem. However, it has two unfortunate side effects. 1) AVI(Xvid/MP3) audio playback breaks in 64bit WMP and MCE, 2) Audio volume on MP4 playback is very low.

along with disabling the Microsoft Video decoder on the SWAP TAB,
disable the Microsoft Audio decoder
disable the Windows DMO codec
set FFDshow for MP2/3
test
if there are problems,
on the Audio TAB, press the button to disable LAV audio
choose to use FFDshow normalization

[rmbolger]

(03-17-2012 04:49 PM)Shark007 Wrote:  along with disabling the Microsoft Video decoder on the SWAP TAB,
disable the Microsoft Audio decoder
disable the Windows DMO codec
set FFDshow for MP2/3
test

Awesome. These steps fix the original side effects of disabling the MS Video decoder.

Unfortunately, I'm now having trouble reproducing the original problem consistently. My two control systems are behaving differently on the same set of files. It's maddening from the perspective of trying to narrow down the original cause. But ultimately it doesn't matter because now I have a wife-friendly workaround that will satisfy while I tinker.

Thanks Shark. =)

[Shark007]

you're welcomed