I've been on the scent of this issue for a few weeks now, but I have reached a brick wall with regards to progressing with a solution, so I'd like to open up my issue to everyone else.
Why do there seem to be problems with remuxing FLV to MP4 since Twitch.tv changed the numbering convention on their file downloads?
What Is The Precise Problem?
Up until recently, I had a 100% success rate with the remuxing of Twitch.tv FLV stream downloads to MP4 which I could then use within video editing software for further modifications.
Recently however, I have found that following this process, the MP4 files created do not play in Windows Media Player and are not recognised by video editing software as a valid format.
What is more confusing is that some files still seem to remux successfully, while others do not. After some investigations, I've found that you can diagnose files that will and won't remux correctly using Media Player Classic (MPC). If a file will remux correctly, opening the raw FLV files in MPC will play the video as normal. If a file will not remux correctly, opening the raw FLV file in MPC will play the video, but no the sound.
Using the process you have described in your tutorial also works for 'old' type FLV files but not for 'new' type FLV files .
What Has Changed?
I noticed that on the 13th January 2013 there was a change to the naming convention for Twitch.tv FLV files that have come from a stream that lasted longer than 30 minutes.
Before, videos longer than 30 minutes were split down into separate video approximately 30 minutes in length, each with their own identifying number in the URL. Now such files also have a period and a number on the end of this URL, signifying the order in which they fit together to create the original video.
For example: -
BEFORE
Part 1 - http://media46.justin.tv/archives/2013-1-12/live_user_thanklessgrind_1358030540.flv
Part 2 - http://media27.justin.tv/archives/2013-1-12/live_user_thanklessgrind_1358032339.flv
AFTER
Part 1 - http://media30.justin.tv/archives/2013-1-16/live_user_thanklessgrind_1358362811.1.flv
Part 2 - http://media30.justin.tv/archives/2013-1-16/live_user_thanklessgrind_1358364618.2.flv
Conclusion
I believe something has changed with the file format along with this change to the filename, but I am yet to discover what. Unfortunately, in the meantime, it seems that it is not possible to remux any FLV files to MP4 for further editing if the file name ends with a '.2' or above.
If you or anyone else has any clues on this issue or knows what might have caused this recent change, it would be great to bounce some ideas around!
Thanks!
Sam
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