Add relative seek.

2 files changed, 329 insertions, 3 deletions

diff --git a/src/Mpeg.cpp b/src/Mpeg.cpp
index bbcc935..2426dff 100644
--- a/src/Mpeg.cpp
+++ b/src/Mpeg.cpp
@@ -15,7 +15,9 @@ void Mpeg::seek(HttpHeader &header)
 {
 	try {
 		std::string position = header.page_params["position"];
-		if (position == "") {
+		std::string relative = header.page_params["relative"];
+
+		if (position.empty() && relative.empty()) {
 			off_t byte_offset = 0;
 			std::string range = header.params["Range"];
 			if((range.length() > 7) && (range.substr(0, 6) == "bytes=")) {
@@ -31,7 +33,15 @@ void Mpeg::seek(HttpHeader &header)
 			}
 		}
 		else {
-			unsigned int position_offset = Util::strtollu(position);
+			unsigned int position_offset;
+			if (!relative.empty()) {
+				int dur = duration();
+				DEBUG("duration : %d", dur);
+				position_offset = (dur * Util::strtollu(relative)) / 100;
+			}
+			else {
+				position_offset = Util::strtollu(position);
+			}
 			if (is_time_seekable && position_offset > 0) {
 				DEBUG("seek to position_offset %ds", position_offset);
 				seek_time((position_offset * 1000) + first_pcr_ms);
@@ -44,3 +54,286 @@ void Mpeg::seek(HttpHeader &header)
 	}
 }
 //----------------------------------------------------------------------
+
+off_t Mpeg::lseek(off_t offset, int whence)
+{
+	if (m_nrfiles < 2)
+		return ::lseek(get_fd(), offset, whence);
+
+	switch (whence) {
+	case SEEK_SET: m_current_offset  = offset; break;
+	case SEEK_CUR: m_current_offset += offset; break;
+	case SEEK_END: m_current_offset  = m_totallength + offset; break;
+	}
+
+	if (m_current_offset < 0)
+		m_current_offset = 0;
+	return m_current_offset;
+}
+//----------------------------------------------------------------------
+
+ssize_t Mpeg::read(off_t offset, void *buf, size_t count)
+{
+	if (offset != m_current_offset) {
+		m_current_offset = this->lseek(offset, SEEK_SET);
+		if (m_current_offset < 0) {
+			return m_current_offset;
+		}
+	}
+	switch_offset(m_current_offset);
+
+	if (m_nrfiles >= 2) {
+		if ((m_current_offset + count) > m_totallength)
+			count = m_totallength - m_current_offset;
+		if (count < 0) {
+			return 0;
+		}
+	}
+
+	int ret = ::read(get_fd(), buf, count);
+	if (ret > 0)
+		m_current_offset = m_last_offset += ret;
+	return ret;
+}
+//----------------------------------------------------------------------
+
+int Mpeg::switch_offset(off_t off)
+{
+	if (m_splitsize) {
+		int filenr = off / m_splitsize;
+		if (filenr >= m_nrfiles)
+			filenr = m_nrfiles - 1;
+//		if (filenr != m_current_file) {
+//			close();
+//			m_fd = open(filenr);
+//			m_last_offset = m_base_offset = m_splitsize * filenr;
+//			m_current_file = filenr;
+//		}
+	}
+	else m_base_offset = 0;
+
+	return (off != m_last_offset) ? (m_last_offset = ::lseek(get_fd(), off - m_base_offset, SEEK_SET) + m_base_offset) : m_last_offset;
+}
+//----------------------------------------------------------------------
+
+void Mpeg::calc_begin()
+{
+	if (!(m_begin_valid || m_futile)) {
+		m_offset_begin = 0;
+		if (!get_pts(m_offset_begin, m_pts_begin, 0))
+			m_begin_valid = 1;
+		else m_futile = 1;
+	}
+	if (m_begin_valid) {
+		m_end_valid = 0;
+	}
+}
+//----------------------------------------------------------------------
+
+void Mpeg::calc_end()
+{
+	off_t end = this->lseek(0, SEEK_END);
+
+	if (llabs(end - m_last_filelength) > 1*1024*1024) {
+		m_last_filelength = end;
+		m_end_valid = 0;
+
+		m_futile = 0;
+	}
+
+	int maxiter = 10;
+
+	m_offset_end = m_last_filelength;
+
+	while (!(m_end_valid || m_futile)) {
+		if (!--maxiter) {
+			m_futile = 1;
+			return;
+		}
+
+		m_offset_end -= 256*1024;
+		if (m_offset_end < 0)
+			m_offset_end = 0;
+
+		off_t off = m_offset_end;
+
+		if (!get_pts(m_offset_end, m_pts_end, 0))
+			m_end_valid = 1;
+		else m_offset_end = off;
+
+		if (!m_offset_end) {
+			m_futile = 1;
+			break;
+		}
+	}
+}
+//----------------------------------------------------------------------
+
+int Mpeg::fix_pts(const off_t &offset, pts_t &now)
+{
+	/* for the simple case, we assume one epoch, with up to one wrap around in the middle. */
+	printf("%s : %d\n", __FUNCTION__, __LINE__);
+
+	calc_begin();
+	if (!m_begin_valid) {
+		return -1;
+	}
+
+	pts_t pos = m_pts_begin;
+	if ((now < pos) && ((pos - now) < 90000 * 10)) {
+		pos = 0;
+		return 0;
+	}
+
+	if (now < pos) /* wrap around */
+		now = now + 0x200000000LL - pos;
+	else now -= pos;
+
+	return 0;
+}
+//----------------------------------------------------------------------
+
+int Mpeg::get_pts(off_t &offset, pts_t &pts, int fixed)
+{
+	int left = 256*1024;
+
+	offset -= offset % 188;
+
+	while (left >= 188) {
+		unsigned char packet[188];
+		if (this->read(offset, packet, 188) != 188) {
+			//break;
+			return -1;
+		}
+		left   -= 188;
+		offset += 188;
+
+		if (packet[0] != 0x47) {
+			int i = 0;
+			while (i < 188) {
+				if (packet[i] == 0x47)
+					break;
+				--offset; ++i;
+			}
+			continue;
+		}
+
+		unsigned char *payload;
+		int pusi = !!(packet[1] & 0x40);
+
+		/* check for adaption field */
+		if (packet[3] & 0x20) {
+			if (packet[4] >= 183)
+				continue;
+			if (packet[4]) {
+				if (packet[5] & 0x10) { /* PCR present */
+					pts  = ((unsigned long long)(packet[ 6]&0xFF)) << 25;
+					pts |= ((unsigned long long)(packet[ 7]&0xFF)) << 17;
+					pts |= ((unsigned long long)(packet[ 8]&0xFE)) << 9;
+					pts |= ((unsigned long long)(packet[ 9]&0xFF)) << 1;
+					pts |= ((unsigned long long)(packet[10]&0x80)) >> 7;
+					offset -= 188;
+					if (fixed && fix_pts(offset, pts))
+						return -1;
+					return 0;
+				}
+			}
+			payload = packet + packet[4] + 4 + 1;
+		}
+		else payload = packet + 4;
+
+		if (!pusi) continue;
+
+		/* somehow not a startcode. (this is invalid, since pusi was set.) ignore it. */
+		if (payload[0] || payload[1] || (payload[2] != 1))
+			continue;
+
+		if (payload[3] == 0xFD) { // stream use extension mechanism defined in ISO 13818-1 Amendment 2
+			if (payload[7] & 1) { // PES extension flag
+				int offs = 0;
+				if (payload[7] & 0x80) // pts avail
+					offs += 5;
+				if (payload[7] & 0x40) // dts avail
+					offs += 5;
+				if (payload[7] & 0x20) // escr avail
+					offs += 6;
+				if (payload[7] & 0x10) // es rate
+					offs += 3;
+				if (payload[7] & 0x8)  // dsm trickmode
+					offs += 1;
+				if (payload[7] & 0x4)  // additional copy info
+					offs += 1;
+				if (payload[7] & 0x2)  // crc
+					offs += 2;
+				if (payload[8] < offs)
+					continue;
+				uint8_t pef = payload[9+offs++]; // pes extension field
+				if (pef & 1) { // pes extension flag 2
+					if (pef & 0x80) // private data flag
+						offs += 16;
+					if (pef & 0x40) // pack header field flag
+						offs += 1;
+					if (pef & 0x20) // program packet sequence counter flag
+						offs += 2;
+					if (pef & 0x10) // P-STD buffer flag
+						offs += 2;
+					if (payload[8] < offs)
+						continue;
+					uint8_t stream_id_extension_len = payload[9+offs++] & 0x7F;
+					if (stream_id_extension_len >= 1) {
+						if (payload[8] < (offs + stream_id_extension_len) )
+							continue;
+						if (payload[9+offs] & 0x80) // stream_id_extension_bit (should not set)
+							continue;
+						switch (payload[9+offs]) {
+						case 0x55 ... 0x5f: // VC-1
+							break;
+						case 0x71: // AC3 / DTS
+							break;
+						case 0x72: // DTS - HD
+							break;
+						default:
+							continue;
+						}
+					}
+					else continue;
+				}
+				else continue;
+			}
+			else continue;
+		}
+		/* drop non-audio, non-video packets because other streams can be non-compliant.*/
+		else if (((payload[3] & 0xE0) != 0xC0) &&  // audio
+			     ((payload[3] & 0xF0) != 0xE0)) {  // video
+			continue;
+		}
+
+		if (payload[7] & 0x80) { /* PTS */
+			pts  = ((unsigned long long)(payload[ 9]&0xE))  << 29;
+			pts |= ((unsigned long long)(payload[10]&0xFF)) << 22;
+			pts |= ((unsigned long long)(payload[11]&0xFE)) << 14;
+			pts |= ((unsigned long long)(payload[12]&0xFF)) << 7;
+			pts |= ((unsigned long long)(payload[13]&0xFE)) >> 1;
+			offset -= 188;
+
+			return (fixed && fix_pts(offset, pts)) ? -1 : 0;
+		}
+	}
+	return -1;
+}
+//----------------------------------------------------------------------
+
+int Mpeg::duration()
+{
+	calc_begin(); calc_end();
+	if (!(m_begin_valid && m_end_valid))
+		return -1;
+	pts_t len = m_pts_end - m_pts_begin;
+
+	if (len < 0)
+		len += 0x200000000LL;
+
+	len = len / 90000;
+	return int(len);
+}
+//----------------------------------------------------------------------
diff --git a/src/Mpeg.h b/src/Mpeg.h
index 780d080..5877f85 100644
--- a/src/Mpeg.h
+++ b/src/Mpeg.h
@@ -14,12 +14,45 @@
 
 class HttpHeader;
 
+typedef long long pts_t;
+
 class Mpeg : public MpegTS
 {
+private:
+	off_t m_splitsize, m_totallength, m_current_offset, m_base_offset, m_last_offset;
+	int m_nrfiles, m_current_file;
+
+	pts_t m_pts_begin, m_pts_end;
+
+	off_t m_offset_begin, m_offset_end;
+	off_t m_last_filelength;
+
+	int m_begin_valid, m_end_valid, m_futile;
+
+	void scan();
+	int switch_offset(off_t off);
+
+	void calc_end();
+	void calc_begin();
+
+	int fix_pts(const off_t &offset, pts_t &now);
+	int get_pts(off_t &offset, pts_t &pts, int fixed);
+
+	int duration();
+	off_t lseek(off_t offset, int whence);
+	ssize_t read(off_t offset, void *buf, size_t count);
+
 public:
 	Mpeg(std::string file, bool request_time_seek) throw (trap)
 		: MpegTS(file, request_time_seek)
-	{}
+	{
+		m_current_offset = m_base_offset = m_last_offset = 0;
+		m_splitsize = m_nrfiles = m_current_file = m_totallength = 0;
+
+		m_pts_begin = m_pts_end = m_offset_begin = m_offset_end = 0;
+		m_last_filelength = m_begin_valid = m_end_valid = m_futile =0;
+	}
+
 	virtual ~Mpeg() throw () {}
 
 	void seek(HttpHeader &header);