Compensate slope on start

The first frames are typically received and decoded with more delay than the others, causing a wrong slope estimation on start. To compensate, assume an initial slope of 1, then progressively use the estimated slope.
Add buffering debugging tools
2021-07-14 00:39:35 +02:00 · 2021-07-14 00:39:35 +02:00 · 2021-07-14 00:39:35 +02:00 · 2021-07-14 00:39:35 +02:00 · 2021-07-14 00:39:35 +02:00 · 2021-07-14 00:39:35 +02:00
4 changed files with 6 additions and 13 deletions
@@ -203,8 +203,6 @@ Add a buffering delay (in milliseconds) before pushing frames. This increases la

 This option is similar to \fB\-\-display\-buffer\fR, but specific to V4L2 sink.

-Default is 0 (no buffering).
-
 .TP
 .BI "\-V, \-\-verbosity " value
 Set the log level ("verbose", "debug", "info", "warn" or "error").
@@ -410,7 +410,7 @@ parse_max_fps(const char *s, uint16_t *max_fps) {
 static bool
 parse_buffering_time(const char *s, sc_tick *tick) {
    long value;
-    bool ok = parse_integer_arg(s, &value, false, 0, 0x7FFFFFFF,
+    bool ok = parse_integer_arg(s, &value, false, 0, 0xFFFFFFFF,
                                "buffering time");
    if (!ok) {
        return false;
@@ -983,11 +983,6 @@ scrcpy_parse_args(struct scrcpy_cli_args *args, int argc, char *argv[]) {
             "See --lock-video-orientation.");
        opts->lock_video_orientation = SC_LOCK_VIDEO_ORIENTATION_INITIAL;
    }
-
-    if (opts->v4l2_buffer && !opts->v4l2_device) {
-        LOGE("V4L2 buffer value without V4L2 sink\n");
-        return false;
-    }
 #else
    if (!opts->display && !opts->record_filename) {
        LOGE("-N/--no-display requires screen recording (-r/--record)");
@@ -5,11 +5,11 @@
 sc_tick
 sc_tick_now(void) {
    // SDL_GetTicks() resolution is in milliseconds, but sc_tick are expressed
-    // in microseconds to store PTS without precision loss.
+    // in microseconds to avoid loosing precision on PTS.
    //
-    // As an alternative, SDL_GetPerformanceCounter() and
-    // SDL_GetPerformanceFrequency() could be used, but:
-    //  - the conversions (avoiding overflow) are expansive, since the
+    // SDL_GetPerformanceCounter()/SDL_GetPerformanceFrequency() could be used,
+    // but:
+    //  - the conversions (to avoid overflow) are not zero-cost, since the
    //    frequency is not known at compile time;
    //  - in practice, we don't need more precision for now.
    return (sc_tick) SDL_GetTicks() * 1000;
@@ -29,7 +29,7 @@ struct sc_video_buffer {

    sc_tick buffering_time;

-    // only if buffering_time > 0
+    // only if buffering_ms > 0
    struct {
        sc_thread thread;
        sc_mutex mutex;
Author	SHA1	Message	Date
Romain Vimont	b454af6808	Compensate slope on start The first frames are typically received and decoded with more delay than the others, causing a wrong slope estimation on start. To compensate, assume an initial slope of 1, then progressively use the estimated slope.	2021-07-14 00:39:35 +02:00
Romain Vimont	2b0399a615	Add buffering debugging tools Output buffering and clock logs by disabling a compilation flag.	2021-07-14 00:39:35 +02:00
Romain Vimont	fb6863068c	Add clock tests The clock rolling sum is not trivial. Test it.	2021-07-14 00:39:35 +02:00
Romain Vimont	5cbcd10356	Add buffering command line options Add --display-buffer and --v4l2-buffer options to configure buffering time.	2021-07-14 00:39:35 +02:00
Romain Vimont	ecf417fc49	Implement buffering To minimize latency (at the cost of jitter), scrcpy always displays a frame as soon as it available, without waiting. However, when recording (--record), it still writes the captured timestamps to the output file, so that the recorded file can be played correctly without jitter. Some real-time use cases might benefit from adding a small latency to compensate for jitter too. For example, few tens of seconds of latency for live-streaming are not important, but jitter is noticeable. Therefore, implement a buffering mechanism (disabled by default) to add a configurable latency delay. PR #2417 <https://github.com/Genymobile/scrcpy/issues/2417>	2021-07-14 00:39:35 +02:00
Romain Vimont	85bc66ad05	Notify new frames via callbacks Currently, a frame is available to the consumer as soon as it is pushed by the producer (which can detect if the previous frame is skipped). Notify the new frames (and frame skipped) via callbacks instead. This paves the way to add (optional) buffering, which will introduce a delay between the time when the frame is produced and the time it is available to be consumed.	2021-07-14 00:39:35 +02:00
Romain Vimont	ed2ac27596	Extract current video_buffer to frame_buffer The current video buffer only stores one pending frame. In order to add a new buffering feature, move this part to a separate "frame buffer". Keep the video_buffer, which currently delegates all its calls to the frame_buffer.	2021-07-14 00:39:35 +02:00
Romain Vimont	70a1b46e13	Rename video_buffer to sc_video_buffer Add a scrcpy-specific prefix.	2021-07-14 00:39:35 +02:00
Romain Vimont	c1eeaa080a	Relax v4l2_sink lock constraints To fix a data race, commit `5caeab5f6d` called video_buffer_push() and video_buffer_consume() under the v4l2_sink lock. Instead, use the previous_skipped indication (initialized with video buffer locked) to lock only for protecting the has_frame flag. This enables the possibility for the video_buffer to notify new frames via callbacks without lock inversion issues.	2021-07-14 00:39:35 +02:00
Romain Vimont	7ae18c3601	Replace delay by deadline in timedwait() The function sc_cond_timedwait() accepted a parameter representing the max duration to wait, because it internally uses SDL_CondWaitTimeout(). Instead, accept a deadline, to be consistent with pthread_cond_timedwait().	2021-07-14 00:39:35 +02:00
Romain Vimont	1ffabc6fcd	Wrap tick API This avoids to use the SDL timer API directly, and will allow to handle generic ticks (possibly negative).	2021-07-14 00:39:35 +02:00