When demuxing, it is called by the demuxer in read_header(). If the
flag AVFMTCTX_NOHEADER is set in s.ctx_flags, then it may also
be called in read_packet().
When muxing, should be called by the user before avformat_write_header().
User is required to call avcodec_close() and avformat_free_context() to
clean up the allocation by avformat_new_stream().
@param s media file handle
@param c If non-NULL, the AVCodecContext corresponding to the new stream
will be initialized to use this codec. This is needed for e.g. codec-specific
defaults to be set, so codec should be provided if it is known.
Add a new stream to a media file.
When demuxing, it is called by the demuxer in read_header(). If the flag AVFMTCTX_NOHEADER is set in s.ctx_flags, then it may also be called in read_packet().
When muxing, should be called by the user before avformat_write_header().
User is required to call avcodec_close() and avformat_free_context() to clean up the allocation by avformat_new_stream().
@param s media file handle @param c If non-NULL, the AVCodecContext corresponding to the new stream will be initialized to use this codec. This is needed for e.g. codec-specific defaults to be set, so codec should be provided if it is known.
@return newly created stream or NULL on error.