Sorry for the double mail. I've been told that my previous mail have not made it to the list. It contained a couple photos which I think may be too big (:S).
Please find a copy of the text below. Sorry for the inconvenience: Hello, > As we are distributing MP4+H264 videos in production, we have been > investigating this issues for a long while. So let me share some comments > about what we found out. > The moov header in an MP4 files *used to *be required to be at the > beginning of the archive, because without that header the video is not > playable. However, if your download server has a pseudo-streaming module > (which I*totally* recommend), the players can first fetch the last part > of the file, where most of the muxers (including ffmpeg) store the moov > header, > and then start downloading the file from the beginning. With a > psudo-streaming module,qt-faststart *only* saves some requests to the > server. The impact in the overall performance is minimum, though. > Of course if you are using Jetty (or any other plain download server with > not pseudostreaming capabilities) you will need to have the moov header > at the beginning of the file if you don't want to wait until all the file > has been downloaded to play it. > You can run qt-faststart by using the existing > CLIWorkflowOperationHandler, but there are some issues to it: > > 1. CLIOperationHandler runs a CLI command *in the admin server*, but > not in the worker(s) where it is expected. > > > 1. You can not specify a certain (set of) tag(s) or flavor(s) to > filter the elements the operation will be applied to, as it happens in > other operations such as "compose". Instead, you need to explicitly specify > all the mediapackage elements on which you want to apply the operation, and > that using a rather cumbersome xpath syntax. > > > 1. qt-faststart generates another file (it does not operate on the > input file directly). Then your script needs to overwrite old file with the > new one, or otherwise create an XML representation of a mediapackage that > includes that result video as a new track, with proper identification to it > (a "qtfaststart" tag, for instance). > > > However our biggest concern is the large amount of time since you start > downloading the video until it is playable *even if the header is at the > beginning of the file*. We are talking about a 4 seconds lag at least, > which gives quite a negative impression in comparison with the streaming > solutions that start playing almost instantly. But this is a matter for > another (long) discussion. 2012/9/26 Rubén Pérez <[email protected]> > Brian, > > As I said, if you have a pseudostreaming server, it is able to fetch the > header at the end of the file. Please see my previous post. ffmpeg always > leaves the moov header at the end of the file. > > Best regards > > > Rubén Pérez > TELTEK Video Research > www.teltek.es > > > > 2012/9/26 Brian O'Hagan <[email protected]> > >> Hi Doug! >> >> Also there is also moovrelocator, which can be used to check the location >> of the file's index and move if needed. Hope this helps: >> http://code.google.com/p/moovrelocator/ >> >> (Also fwiw: We use an Ffmpeg encoding profile (x264) for assets served >> via pseudostreaming and byte range requests, and time and seek calls work >> ok, implying the index is at the front of the file.) >> >> >> -- >> Brian O'Hagan >> >> On Wednesday, September 26, 2012 at 5:54 AM, Hall, Douglas wrote: >> >> Hi Chris, >> >> When I try to play my MP4's in the engage player via download, the video >> will not start playing until the entire file has downloaded. If I encode >> to FLV the video will start playing immediately. I have read the reason >> for this is that H.264/MP4 files contain metadata at the end of the file >> which the flash player needs before it can start playing. Using >> qt-faststart to move this metadata to the beginning of the file is >> supposed to resolve this issue. Has anyone had the same experience? Is >> there a better solution? >> >> Thanks, >> >> - Doug >> >> On 9/25/12 11:48 PM, "Christopher Brooks" <[email protected]> wrote: >> >> On Wed, 26 Sep 2012 03:10:47 +0000 >> "Hall, Douglas" <[email protected]> wrote: >> >> Hi, >> >> Is anyone using qt-faststart to move the index information from the >> end of an H.264/MP4 to the beginning? If so, how are you calling it >> from your Matterhorn workflows? Is there a better way of doing this >> without using qt-faststart? >> >> Best regards, >> >> - Doug >> >> >> Why would you do this? For mp4 streaming hinting? >> >> Chris >> >> >> _______________________________________________ >> Matterhorn-users mailing list >> [email protected] >> http://lists.opencastproject.org/mailman/listinfo/matterhorn-users >> >> >> >> _______________________________________________ >> Matterhorn-users mailing list >> [email protected] >> http://lists.opencastproject.org/mailman/listinfo/matterhorn-users >> >> >
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