Hello, there is a problem with the definition of the frame type pjmedia_frame_ext which hinders its use. If in the standard type pjmeda_frame the type field set to PJMEDIA_TYPE_EXTENDED, the frame can be casted to pjmedia_frame_ext. This type allows the use of frames consising of subframes and is used for encoded audio. A problem arises, if a processing block supplies a frame with type PJMEDIA_TYPE_NONE and the receiver has to cast this to EXTENDED. The extend frames must have its payload directly after the pjmedia_frame_ext structure. From pjmedia/types.h: * This structure may contain more than one audio frames, which subsequently * will be called subframes in this structure. The subframes section * immediately follows the end of this structure, and each subframe is * represented by pjmedia_frame_ext_subframe structure. Every next * subframe immediately follows the previous subframe, and all subframes * are byte-aligned although its payload may not be byte-aligned. In the normal pjmedia_frame there is a pointer pointing to the corresponding data buffer. Both frames are quite similar, but very different in the approch to storing the data. Thus if I cast a pjmedia_frame to pjmedia_frame_ext, I have to take for granted, that there is the space for data buffer in the memory directly after the frame structure. This can be observed if using the switch_board module. It supplies a pjmedia_frame with type equal to PJMEDIA_TYPE_NONE, but expects a frame with type PJMEDIA_TYPE_EXTENED back. In this case, there is no problem, because the memory for the frame has been allocated accordingly, but not all block support this now. My suggestion would be to change the requirement that the data is directly behind the pjmedia_frame_ext structure to using the buffer pointer in the base structure of the pjmedia_frame_ext structure. It would then point to the sub frames in the same the way it is handeled by the simple frames. This would require slight changes in the functions in pjmedia/types.h, e.g. pjmedia_frame_ext_append_subframe. Let me know what you think. If my proposal may be useful, I can offer the corresponding patches. Regards, Thomas Falk
