Tuesday, December 03, 2013

youtube download failure and solution

Yesterday, for the first time, the youtube mp4 file I downloaded using Flashgot Firefox add-on did not work. Then, another file I downloaded also appeared to be "corrupted". Googling got me this page which indicated that the problem was that youtube was using MPEG-DASH streaming, and so the files were not downloaded correctly.

Tried using Youtube Center as indicated in this Dave's tip, but even with the Youtube Center firefox add-on, when downloaded with flashgot, the downloaded file still had issues.

Then tried the old faithful - the KeepVid.com bookmarklet. Finally, video downloaded with that worked fine. Of course, a caution for keepvid.com users, you have to click on the download link on the right of the text box and not on the bigger "Free Download" link below, which is actually an ad for another downloader product. And keepvid needs to run a java applet.

What could I do with the "corrupted" downloaded videos? This post indicated that GPAC might be able to help. (BTW, Nirsoft's freeware tools are really nice!)

And indeed, the mp4box utility contained in the GPAC download did the trick - made the video readable by AVIDemux using
MP4Box -add file.mp4 out_file.mp4

Even though the documentation said that the -isma switch would make the video compatible with most players,  doing
MP4Box -isma file.mp4

had a similar result as the -add above, with the file being readable by VLC and AVIDemux, but not directshow. Used Avidemux to re-encode the file as HuffYUV, then directshow could read it. Using Avidemux in copy mode was not enough. And after all this, there was no audio stream. Apparently, the downloaded file contained only the video stream and not the audio.

So, the best option would be to re-download using Keepvid or something like that, unless you need only the images and not the sound, like in my case.

Edit: Just noting that mkv files produced in "Copy" mode using Avidemux could be played by TheKMplayer, VLC etc, but not directshow/Windows Media Player. avi files produced in the same way could not be played by TheKMPlayer either, though VLC could.

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