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 video you're experiencing issues with.
Playback Performance Issues
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.
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
1) 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, click 'Stop logging', a new tab will open
6) Share the profile, with the button at the top right of this new tab (either upload or send privately)
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.