Recording and MIME types (Re: Mediastream Recording implementation)

Forking the subject line....

On 07/16/2013 10:10 PM, Travis Leithead wrote:
>
> In the Blob vs. ArrayBuffer discussion... there is a lot of room for 
> implementation details on how the data can be paged in and out of 
> memory on demand. Certainly not all the data need be in memory 
> /initially/ with either return type. The Blob does require a bit more 
> work to begin addressing it if in-memory manipulation of the data is 
> your goal (this usually involves Blob->ArrayBufferView); if your goal 
> is to simply send the data along to a server via XHR, then Blob is 
> convenient, because the mimeType can travel along with the data 
> easily. I don't know that we ever pinned down the question about what 
> the mimeType will be though.
>

We may have a problem here if we expect a MIME type for each blob.
MIME types are usually defined in terms of the whole file (or the whole 
stream for RTP MIME types), including any headers that occur only at the 
beginning.

My expectation is certainly that the MIME type of the file that results 
from concatenating all the blobs needs to be clearly defined and useful, 
but I don't see a reason to have a MIME type for each blob.

If Blobs have MIME types in general, that may be an argument against 
using Blob.