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.

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);