Err 404 when updating podcast
Chunk size restriction: All chunks must be a multiple of 256 KB (256 x 1024 bytes) in size, except for the final chunk that completes the upload.If you use chunking, it is important to keep the chunk size as large as possible to keep the upload efficient.header, as shown in the above example response, is the session URI you'll use as the HTTP endpoint for doing the actual file upload or querying the upload status.
However, you might need to use chunking to reduce the amount of data transferred in any single request.
3) Resume the upload from the point where it left off.
The following request resumes the upload by sending the remaining bytes of the file, starting at byte 43.
This is helpful when there is a fixed time limit for individual requests, as is true for certain classes of Google App Engine requests.
It also lets you do things like providing upload progress indications for legacy browsers that don't have upload progress support by default.