Add -write-first-frame-ts switch

Add -write-first-frame-ts switch that creates a .ts file next to the output
file with values from CLOCK_MONOTONIC and CLOCK_REALTIME corresponding to the
first frame to be able to synchronize video with other timestamped data.

gpu-screen-recorder.1

@@ -372,6 +372,14 @@ It's recommended to also use the option
 when this is set to
 .B yes
 to only encode frames when the screen content updates to lower GPU and video encoding usage when the system is idle.
+.TP
+.BI \-write\-first\-frame\-ts " yes|no"
+When enabled, writes a timestamp file with extra extension \fI.ts\fR next to the output video containing:
+.nf
+monotonic_microsec	realtime_microsec
+<monotonic_microsec>	<realtime_microsec>
+.fi
+(default: no). Ignored for livestreaming and when output is piped.
 .SS Output Options
 .TP
 .BI \-o " output"

include/args_parser.h

@@ -8,7 +8,7 @@
 
 typedef struct gsr_egl gsr_egl;
 
-#define NUM_ARGS 36
+#define NUM_ARGS 37
 
 typedef enum {
     GSR_CAPTURE_SOURCE_TYPE_WINDOW,
@@ -97,6 +97,7 @@ typedef struct {
     bool restore_portal_session;
     bool restart_replay_on_save;
     bool overclock;
+    bool write_first_frame_ts;
     bool is_livestream;
     bool is_output_piped;
     bool low_latency_recording;

include/encoder/encoder.h

@@ -20,6 +20,8 @@ typedef struct {
     AVStream *stream;
     int64_t start_pts;
     bool has_received_keyframe;
+    char *first_frame_ts_filepath;
+    bool first_frame_ts_written;
 } gsr_encoder_recording_destination;
 
 typedef struct {
@@ -43,5 +45,6 @@ void gsr_encoder_receive_packets(gsr_encoder *self, AVCodecContext *codec_contex
 /* Returns the id to the recording destination, or -1 on error */
 size_t gsr_encoder_add_recording_destination(gsr_encoder *self, AVCodecContext *codec_context, AVFormatContext *format_context, AVStream *stream, int64_t start_pts);
 bool gsr_encoder_remove_recording_destination(gsr_encoder *self, size_t id);
+bool gsr_encoder_set_recording_destination_first_frame_ts_filepath(gsr_encoder *self, size_t id, const char *filepath);
 
 #endif /* GSR_ENCODER_H */

src/args_parser.c

@@ -196,7 +196,7 @@ static void usage_header(void) {
            "[-bm auto|qp|vbr|cbr] [-cr limited|full] [-tune performance|quality] [-df yes|no] [-sc <script_path>] [-p <plugin_path>] "
            "[-cursor yes|no] [-keyint <value>] [-restore-portal-session yes|no] [-portal-session-token-filepath filepath] [-encoder gpu|cpu] "
            "[-fallback-cpu-encoding yes|no] [-o <output_file>] [-ro <output_directory>] [-ffmpeg-opts <options>] [--list-capture-options [card_path]] "
-           "[--list-audio-devices] [--list-application-audio] [--list-v4l2-devices] [-low-power yes|no] [-v yes|no] [-gl-debug yes|no] [--version] [-h|--help]\n", program_name);
+           "[--list-audio-devices] [--list-application-audio] [--list-v4l2-devices] [-write-first-frame-ts yes|no] [-low-power yes|no] [-v yes|no] [-gl-debug yes|no] [--version] [-h|--help]\n", program_name);
     fflush(stdout);
 }
 
@@ -255,6 +255,7 @@ static bool args_parser_set_values(args_parser *self) {
     self->restart_replay_on_save = args_get_boolean_by_key(self->args, NUM_ARGS, "-restart-replay-on-save", false);
     self->overclock = args_get_boolean_by_key(self->args, NUM_ARGS, "-oc", false);
     self->fallback_cpu_encoding = args_get_boolean_by_key(self->args, NUM_ARGS, "-fallback-cpu-encoding", false);
+    self->write_first_frame_ts = args_get_boolean_by_key(self->args, NUM_ARGS, "-write-first-frame-ts", false);
     self->low_power = args_get_boolean_by_key(self->args, NUM_ARGS, "-low-power", false);
 
     self->audio_bitrate = args_get_i64_by_key(self->args, NUM_ARGS, "-ab", 0);
@@ -432,6 +433,10 @@ static bool args_parser_set_values(args_parser *self) {
 
     self->is_output_piped = strcmp(self->filename, "/dev/stdout") == 0;
     self->low_latency_recording = self->is_livestream || self->is_output_piped;
+    if(self->write_first_frame_ts && (self->is_livestream || self->is_output_piped)) {
+        fprintf(stderr, "gsr warning: -write-first-frame-ts is ignored for livestreaming or when output is piped\n");
+        self->write_first_frame_ts = false;
+    }
 
     self->replay_recording_directory = args_get_value_by_key(self->args, NUM_ARGS, "-ro");
 
@@ -536,6 +541,7 @@ bool args_parser_parse(args_parser *self, int argc, char **argv, const args_hand
     self->args[arg_index++] = (Arg){ .key = "-ffmpeg-opts",                   .optional = true,  .list = false, .type = ARG_TYPE_STRING };
     self->args[arg_index++] = (Arg){ .key = "-ffmpeg-video-opts",             .optional = true,  .list = false, .type = ARG_TYPE_STRING };
     self->args[arg_index++] = (Arg){ .key = "-ffmpeg-audio-opts",             .optional = true,  .list = false, .type = ARG_TYPE_STRING };
+    self->args[arg_index++] = (Arg){ .key = "-write-first-frame-ts",          .optional = true,  .list = false, .type = ARG_TYPE_BOOLEAN };
     self->args[arg_index++] = (Arg){ .key = "-low-power",                     .optional = true,  .list = false, .type = ARG_TYPE_BOOLEAN };
     assert(arg_index == NUM_ARGS);
 

src/encoder/encoder.c

@@ -3,10 +3,37 @@
 
 #include <string.h>
 #include <stdio.h>
+#include <stdlib.h>
+#include <inttypes.h>
+#include <time.h>
+#include <errno.h>
 
 #include <libavcodec/avcodec.h>
 #include <libavformat/avformat.h>
 
+static uint64_t clock_gettime_microseconds(clockid_t clock_id) {
+    struct timespec ts;
+    ts.tv_sec = 0;
+    ts.tv_nsec = 0;
+    clock_gettime(clock_id, &ts);
+    return (uint64_t)ts.tv_sec * 1000000ULL + (uint64_t)ts.tv_nsec / 1000ULL;
+}
+
+static void gsr_write_first_frame_timestamp_file(const char *filepath) {
+    const uint64_t evdev_compatible_ts = clock_gettime_microseconds(CLOCK_MONOTONIC);
+    const uint64_t unix_time_microsec = clock_gettime_microseconds(CLOCK_REALTIME);
+
+    FILE *file = fopen(filepath, "w");
+    if(!file) {
+        fprintf(stderr, "gsr warning: failed to open timestamp file '%s': %s\n", filepath, strerror(errno));
+        return;
+    }
+
+    fputs("monotonic_microsec\trealtime_microsec\n", file);
+    fprintf(file, "%" PRIu64 "\t%" PRIu64 "\n", evdev_compatible_ts, unix_time_microsec);
+    fclose(file);
+}
+
 bool gsr_encoder_init(gsr_encoder *self, gsr_replay_storage replay_storage, size_t replay_buffer_num_packets, double replay_buffer_time, const char *replay_directory) {
     memset(self, 0, sizeof(*self));
     self->num_recording_destinations = 0;
@@ -39,6 +66,16 @@ bool gsr_encoder_init(gsr_encoder *self, gsr_replay_storage replay_storage, size
 }
 
 void gsr_encoder_deinit(gsr_encoder *self)  {
+    if(self->file_write_mutex_created)
+        pthread_mutex_lock(&self->file_write_mutex);
+    for(size_t i = 0; i < self->num_recording_destinations; ++i) {
+        free(self->recording_destinations[i].first_frame_ts_filepath);
+        self->recording_destinations[i].first_frame_ts_filepath = NULL;
+        self->recording_destinations[i].first_frame_ts_written = false;
+    }
+    if(self->file_write_mutex_created)
+        pthread_mutex_unlock(&self->file_write_mutex);
+
     if(self->replay_buffer) {
         pthread_mutex_lock(&self->replay_mutex);
         gsr_replay_buffer_destroy(self->replay_buffer);
@@ -94,6 +131,11 @@ void gsr_encoder_receive_packets(gsr_encoder *self, AVCodecContext *codec_contex
                 else if(!recording_destination->has_received_keyframe)
                     continue;
 
+                if(recording_destination->first_frame_ts_filepath && !recording_destination->first_frame_ts_written) {
+                    gsr_write_first_frame_timestamp_file(recording_destination->first_frame_ts_filepath);
+                    recording_destination->first_frame_ts_written = true;
+                }
+
                 av_packet->pts = pts - recording_destination->start_pts;
                 av_packet->dts = pts - recording_destination->start_pts;
 
@@ -148,6 +190,8 @@ size_t gsr_encoder_add_recording_destination(gsr_encoder *self, AVCodecContext *
     recording_destination->stream = stream;
     recording_destination->start_pts = start_pts;
     recording_destination->has_received_keyframe = false;
+    recording_destination->first_frame_ts_filepath = NULL;
+    recording_destination->first_frame_ts_written = false;
 
     ++self->recording_destination_id_counter;
     ++self->num_recording_destinations;
@@ -161,6 +205,9 @@ bool gsr_encoder_remove_recording_destination(gsr_encoder *self, size_t id) {
     pthread_mutex_lock(&self->file_write_mutex);
     for(size_t i = 0; i < self->num_recording_destinations; ++i) {
         if(self->recording_destinations[i].id == id) {
+            free(self->recording_destinations[i].first_frame_ts_filepath);
+            self->recording_destinations[i].first_frame_ts_filepath = NULL;
+            self->recording_destinations[i].first_frame_ts_written = false;
             self->recording_destinations[i] = self->recording_destinations[self->num_recording_destinations - 1];
             --self->num_recording_destinations;
             found = true;
@@ -170,3 +217,26 @@ bool gsr_encoder_remove_recording_destination(gsr_encoder *self, size_t id) {
     pthread_mutex_unlock(&self->file_write_mutex);
     return found;
 }
+
+bool gsr_encoder_set_recording_destination_first_frame_ts_filepath(gsr_encoder *self, size_t id, const char *filepath) {
+    if(!filepath)
+        return false;
+
+    bool found = false;
+    pthread_mutex_lock(&self->file_write_mutex);
+    for(size_t i = 0; i < self->num_recording_destinations; ++i) {
+        if(self->recording_destinations[i].id == id) {
+            char *filepath_copy = strdup(filepath);
+            if(!filepath_copy)
+                break;
+
+            free(self->recording_destinations[i].first_frame_ts_filepath);
+            self->recording_destinations[i].first_frame_ts_filepath = filepath_copy;
+            self->recording_destinations[i].first_frame_ts_written = false;
+            found = true;
+            break;
+        }
+    }
+    pthread_mutex_unlock(&self->file_write_mutex);
+    return found;
+}

src/main.cpp

@@ -3988,7 +3988,11 @@ int main(int argc, char **argv) {
 
     if(video_stream) {
         avcodec_parameters_from_context(video_stream->codecpar, video_codec_context);
-        gsr_encoder_add_recording_destination(&encoder, video_codec_context, av_format_context, video_stream, 0);
+        const size_t video_destination_id = gsr_encoder_add_recording_destination(&encoder, video_codec_context, av_format_context, video_stream, 0);
+        if(arg_parser.write_first_frame_ts && video_destination_id != (size_t)-1) {
+            std::string ts_filepath = std::string(arg_parser.filename) + ".ts";
+            gsr_encoder_set_recording_destination_first_frame_ts_filepath(&encoder, video_destination_id, ts_filepath.c_str());
+        }
     }
 
     int audio_max_frame_size = 1024;
@@ -4527,6 +4531,11 @@ int main(int argc, char **argv) {
                 replay_recording_start_result = start_recording_create_streams(replay_recording_filepath.c_str(), arg_parser, video_codec_context, audio_tracks, hdr, video_sources);
                 if(replay_recording_start_result.av_format_context) {
                     const size_t video_recording_destination_id = gsr_encoder_add_recording_destination(&encoder, video_codec_context, replay_recording_start_result.av_format_context, replay_recording_start_result.video_stream, video_frame->pts);
+                    if(arg_parser.write_first_frame_ts && video_recording_destination_id != (size_t)-1) {
+                        std::string ts_filepath = replay_recording_filepath + ".ts";
+                        gsr_encoder_set_recording_destination_first_frame_ts_filepath(&encoder, video_recording_destination_id, ts_filepath.c_str());
+                    }
+
                     if(video_recording_destination_id != (size_t)-1)
                         replay_recording_items.push_back(video_recording_destination_id);