Media Debugging Tips

Diagnosing and Reporting Media Playback Issues in Firefox

Basic Media Playback Issues

For simple playback issues (videos on popular sites that fail to play back properly), the first place to start is to check the web developer console for error messages related to format issues. If you see messages here related to media playback errors, please file a Bugzilla report, note any errors you see in the console, and please include the URL to the audio or video you're experiencing issues with.

About:support Text

When filing a Bugzilla bug, please post your about:support text. This provides a great deal of information about your graphics hardware, video hardware support, and much more.

1) Open a tab and visit about:support
2) Click 'Copy Text to Clipboard'
3) Paste this text in your Bugzilla bug comment and post.

Playback Performance Issues

Generating Performance Profiles

For playback performance issues and general media playback problems, capturing and reporting a Firefox Performance Profile can help Mozilla developers diagnose the issue. Please visit profiler.firefox.com to access the profiling feature in Firefox. We also have a Firefox Profiler Getting Started Guide to learn how to record a profile. Note, before recording, please select the 'Media' setting in the profiler toolbar dropdown menu. Once you have a profile recorded of the media playback issue, you can post the resulting profile url to your Bugzilla report for analysis.

Profiler Quick Start

1) Visit https://profiler.firefox.com/ and enable the Profiler toolbar button
2) Click the toolbar button down arrow and select 'Media' in the Settings drop down.
3) Open a tab and visit the page with the affected media content.
4) Click the Profiler toolbar main button to start recording.
5) Play the media until the issue you are seeing manifests.
6) Click the Profiler toolbar button again to stop recording.
7) When a new Profile tab opens, click the upload profile button on the upper right.
8) Copy the resulting profile URL and post this to your Bugzilla report.

Youtube Stats For Nerds

For Youtube playback performance issues, right click the video and select Stats for Nerds. You can select the text in this panel and post it your Bugzilla bug, or grab a screenshot using the Firefox screenshot tool and add the resulting image as an attachment to your bug. This information can be informative for engineers in understanding what video format and resolution you are viewing.

Advanced Diagnosis

In some cases developers will ask reporters to capture detailed media processing logs. This can help diagnose low level content format problems or incompatibilities. If you have already reported a bug in Bugzilla, you can capturing detailed logging as well to help Mozilla engineers diagnose the problem.

General Media Playback Logging Steps

Install Firefox Nightly on the test device and open the browser. The test device should be a clean system that has not had Firefox installed on it prior. If the test device does have existing Firefox installs, open Firefox Nightly using a command line console with the -p command line parameter. This will open the profile manager window. Create a new profile for testing purposes, which can be deleted after testing is complete.

1) Open the browser with your test profile.

2) Open a tab and visit https://profiler.firefox.com/ and enable the Firefox Profiler Button. In the dropdown menu on the button, select the 'Media' setting.

2) Open a tab and visit about:logging
2) In the 'Logging preset:' drop down select 'Media Playback'
3) Click 'Start Logging' at the top of the page
4) Reproduce the issue
5) Go back to the about:logging page and click 'Stop logging'. (In a moment, a new performance profile tab will open.)
6) Share the profile (top right of the performance tab) and copy the resulting url.

Share this url in Bugzilla for engineers to analyze.

These instructions in video: https://paul.cx/public/about-logging-presentation.webm

DRM Related Logging Steps

For DRM content (Amazon Prime, Netflix) it can be helpful to generate EME related logging. The steps to produce these logs are bit more involved compared to basic media playback logging but are worth the effort when tracking down these types of issues. Try these steps:

1) Open a command console and browse to your install location for Firefox.
2) Enter 'set MOZ_DISABLE_GMP_SANDBOX=1' in the console
3) Launch Firefox from the command console (firefox.exe (return))
4) In the browser, open a tab and visit about:logging
5) Enter 'GMP:5,EME:5' in the 'new log modules' text edit and click on 'Set Log Modules'
6) Under Output choose 'Logging to a file' and choose a suitable temp path and then click 'Set Log File'.

In the temp dir, you should get two logs (something like 'emelog.txt-child.23884.moz_log' and 'emelog.txt-main.23435.moz_log'). Post these to your Bugzilla report.