[FFmpeg-user] Question on implementing a custom IO callback in ByteIOContext.
dwkang at camars.kaist.ac.kr
Thu Sep 8 06:56:18 CEST 2011
I realized I am using very old version of ffmpeg and found out there is
"seekable" flag in AVIOContext struct in the current code. This looks like
what I wanted. =) Setting it to 0 seems to work for our usage.
* A combination of AVIO_SEEKABLE_ flags or 0 when the stream is not
On Wed, Sep 7, 2011 at 2:27 PM, Dongwon Kang <dwkang at camars.kaist.ac.kr>wrote:
> Hi all,
> I am trying to implement custom IO call backs by using ByteIOContext in
> avio.h in order to support http sources.
> The implementation of the most callbacks were pretty much straight forward,
> but I faced a problem while handling seek() operation with SEEK_END flag.
> The problem is that there are some cases that we don't know the actual size
> of the source. (e.g. http source which chunked transfer encoding<http://en.wikipedia.org/wiki/Chunked_transfer_encoding>
> Regarding the callback for seek operation, I found some article which says:
> "int64_t SeekFunc(void *opaque, int64_t offset<http://cekirdek.pardus.org.tr/~ismail/ffmpeg-docs/metadata__compat_8c.html#ed7ea92f45bd273dde380a45ddced592>,
> int whence) ;
> you must return the current position of your stream in bytes (that is,
> after the seeking is performed). If the seek has failed you must return <0."
> So, my question is:
> 1. Will it be okay to return -1 if we don't know the actual size of the
> 2. If so, will the ffmpeg demux code just fail to demux the source or treat
> it as streaming source and continue parsing?
> Any comments are welcome!
> Dongwon Kang
CA Lab, Div of CS, Dept of EECS, KAIST
dwkang at camars.kaist.ac.kr (official)
dongwon.kang at gmail.com (non-official)
+82) 42-869-5578 +82) 16-705-2950
More information about the ffmpeg-user