Speed up MP3Extractor using cached reads (31d8a03e) · Commits · e / os / android_frameworks_base

media/libstagefright/MP3Extractor.cpp

+33 −4

Original line number	Diff line number	Diff line
		@@ -228,22 +228,47 @@ static bool Resync(

		off64_t pos = *inout_pos;
		bool valid = false;

		const size_t kMaxReadBytes = 1024;
		const size_t kMaxBytesChecked = 128 * 1024;
		uint8_t buf[kMaxReadBytes];
		ssize_t bytesToRead = kMaxReadBytes;
		ssize_t totalBytesRead = 0;
		ssize_t remainingBytes = 0;
		bool reachEOS = false;
		uint8_t *tmp = buf;

		do {
		if (pos >= inout_pos + 128 1024) {
		if (pos >= *inout_pos + kMaxBytesChecked) {
		// Don't scan forever.
		LOGV("giving up at offset %ld", pos);
		break;
		}

		uint8_t tmp[4];
		if (source->readAt(pos, tmp, 4) != 4) {
		if (remainingBytes < 4) {
		if (reachEOS) {
		break;
		} else {
		memcpy(buf, tmp, remainingBytes);
		bytesToRead = kMaxReadBytes - remainingBytes;
		totalBytesRead = source->readAt(pos, buf + remainingBytes, bytesToRead);
		if (totalBytesRead <= 0) {
		break;
		}
		reachEOS = (totalBytesRead != bytesToRead);
		totalBytesRead += remainingBytes;
		remainingBytes = totalBytesRead;
		tmp = buf;
		continue;
		}
		}

		uint32_t header = U32_AT(tmp);

		if (match_header != 0 && (header & kMask) != (match_header & kMask)) {
		++pos;
		++tmp;
		--remainingBytes;
		continue;
		}

		@@ -253,6 +278,8 @@ static bool Resync(
		header, &frame_size,
		&sample_rate, &num_channels, &bitrate)) {
		++pos;
		++tmp;
		--remainingBytes;
		continue;
		}

		@@ -303,6 +330,8 @@ static bool Resync(
		}

		++pos;
		++tmp;
		--remainingBytes;
		} while (!valid);

		return valid;