Compute relative PTS on the client-side

The PTS received by MediaCodec are expressed relative to an arbitrary
clock origin. We consider the PTS of the first frame to be 0, and the
PTS of every other frame is relative to this first PTS (note that the
PTS is only used for recording, it is ignored for mirroring).

For simplicity, this relative PTS was computed on the server-side.

To prepare support for multiple stream (video and audio), send the
packet with its original PTS, and handle the PTS offset on the
client-side (by the recorder).

Since we can't know in advance which stream will produce the first
packet with the lowest PTS (a packet received later on one stream may
have a PTS lower than a packet received earlier on another stream),
computing the PTS on the server-side would require unnecessary waiting.
This commit is contained in:
Romain Vimont
2023-02-01 21:56:43 +01:00
parent d7f3683a1b
commit 653387acdb
3 changed files with 20 additions and 5 deletions

View File

@@ -42,7 +42,6 @@ public class ScreenEncoder implements Device.RotationListener {
private final int maxFps;
private final boolean sendFrameMeta;
private final boolean downsizeOnError;
private long ptsOrigin;
private boolean firstFrameSent;
private int consecutiveErrors;
@@ -218,10 +217,7 @@ public class ScreenEncoder implements Device.RotationListener {
if ((bufferInfo.flags & MediaCodec.BUFFER_FLAG_CODEC_CONFIG) != 0) {
pts = PACKET_FLAG_CONFIG; // non-media data packet
} else {
if (ptsOrigin == 0) {
ptsOrigin = bufferInfo.presentationTimeUs;
}
pts = bufferInfo.presentationTimeUs - ptsOrigin;
pts = bufferInfo.presentationTimeUs;
if ((bufferInfo.flags & MediaCodec.BUFFER_FLAG_KEY_FRAME) != 0) {
pts |= PACKET_FLAG_KEY_FRAME;
}