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Http Dynamic Streaming

Thread posted 05/01/12 by gosuperninja
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Title
Http Dynamic Streaming

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I'v started to add HTTP Dynamic Streaming support into FFMPEG. In the process I found something very odd and would appreciate any feedback or insight. I started to stripping atoms out of the fragments generated by the adobe fragment tool. I did this to find the initial minimum atoms used in the OSMF to play a fragment stream. I followed adobes F4V doc and read what as manidotry and what wasn't, but I wanted to test it against the OSMF implementation. What I discovered was that I stripped every atom, except the MDAT atom, and OSMF was still able to play the fragments. I'm confused because I thought the TRAF atoms held the location and timing of each from with in the fragment file. So how is OSMF able to play the file. My only thought was that the data in the MDAT isnt' just encoded video/audio. But there is some addition container data in there. Any ideas?

Comments

posted 05/01/12 by gosuperninja | Report Abuse I figured this out, so incase anyone wants to know. The data in the MDATA atom are the audio and video frames with FLV tags. It's similar to a FLV file except it doesn't have the FLV file header and there isn't a "previous tag size" between each tag. I'm not confident about the "previous tag size" but that is what is appears to be. I can't find in the documentation anywhere it specifically states that the frames in the MDAT have FLV tags, but I remember reading something that hinted at that. If anyone knows otherwise, please let me know.