freeswitch/src/mod/applications/mod_mp4/mp4_helper.cpp

/*

The contents of this file are subject to the Mozilla Public License
Version 1.1 (the "License"); you may not use this file except in
compliance with the License. You may obtain a copy of the License at
http://www.mozilla.org/MPL/

Software distributed under the License is distributed on an "AS IS"
basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the
License for the specific language governing rights and limitations
under the License.

The Original Code is MP4 Helper Library to the Freeswitch MP4 Module.

The Initial Developer of the Original Code is 
Paulo Rogério Panhoto <paulo@voicetechnology.com.br>.
Portions created by the Initial Developer are Copyright (C)
the Initial Developer. All Rights Reserved.

Contributors:

	Seven Du <dujinfang@gmail.com>
*/

#include "mp4_helper.hpp"

namespace MP4
{
	
	Context::Context(const char * file, bool newFile)
	{
		if(newFile) create(file);
		else open(file);
	}
	
	Context::~Context()
	{
		close();
	}

	void Context::open(const char * file)
	{
		fh = MP4Read(file);
		if (fh == MP4_INVALID_FILE_HANDLE) throw Exception(file, "Open failed");
		getTracks(file);
	}
	
	void Context::create(const char * file)
	{
		fh = MP4Create(file);
		if (fh == MP4_INVALID_FILE_HANDLE) throw Exception(file, "Create file failed");
	}

	void Context::close()
	{
		if (!isOpen()) return;
		MP4Close(fh);
	}

	void Context::getTracks(const char * file)
	{
		int i = 0;
		bool audioTrack = false, videoTrack = false;

		if (!isOpen()) throw Exception(file, "File is closed.");

		for (;;)
		{
			TrackProperties track;
			if((track.hint = MP4FindTrackId(fh, i++, MP4_HINT_TRACK_TYPE, 0)) == MP4_INVALID_TRACK_ID) break;

			MP4GetHintTrackRtpPayload(fh, track.hint, &track.codecName, &track.payload, NULL, NULL);

			track.track = MP4GetHintTrackReferenceTrackId(fh, track.hint);
			if(track.track == MP4_INVALID_TRACK_ID) continue;
			track.clock = MP4GetTrackTimeScale(fh, track.hint);

			if (!strcmp(MP4GetTrackType(fh, track.track), MP4_AUDIO_TRACK_TYPE)) {
				audioTrack = true;

				if(!strncmp(track.codecName, "PCM", 3))
					track.packetLength = 20;
				else
					track.packetLength = track.clock = 0;

				audio = track;
			} else if (!strcmp(MP4GetTrackType(fh, track.track), MP4_VIDEO_TRACK_TYPE)) {
				videoTrack = true;

				const char * sdp = MP4GetHintTrackSdp(fh, track.hint);
				const char * fmtp = strstr(sdp, "fmtp");

				if (fmtp) {
					// finds beginning of 'fmtp' value;
					for(fmtp += 5; *fmtp != ' '; ++fmtp);
					++fmtp;

					const char * eol = fmtp;
					for(;*eol != '\r' && *eol != '\n'; ++eol);
					video.fmtp = std::string(fmtp, eol);
				}
				video.track = track;
			}
		}

		if (!audioTrack || !videoTrack) throw Exception(file, "Missing audio/video track.");
	}

	bool Context::getVideoPacket(void * buffer, u_int & size, u_int & ts)
	{
		return getPacket(video.track.hint, video.track.runtime, true, buffer, size, ts);
	}

	bool Context::getAudioPacket(void * buffer, u_int & size, u_int & ts)
	{
		return getPacket(audio.hint, audio.runtime, false, buffer, size, ts);
	}

	bool Context::getPacket(MP4TrackId hint, RuntimeProperties & rt,
				bool header, void * buffer, u_int & size, u_int & ts)
	{
		if (rt.frame == 0 || rt.packet == rt.packetsPerFrame) {
			++rt.frame;
			if(!MP4ReadRtpHint(fh, hint, rt.frame, &rt.packetsPerFrame))
				return false;
			rt.packet = 0;
			rt.last_frame = MP4GetSampleTime(fh, hint, rt.frame);
		}

		ts = rt.last_frame;
		if (!MP4ReadRtpPacket(fh, hint, rt.packet, (u_int8_t **) &buffer, &size, 0, header, true)) return false;
		++rt.packet;
		return true;
	}
}