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fix: wrong subtitle timecode on certain SRT files

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This commit is contained in:
minjaesong
2025-11-15 19:54:53 +09:00
parent 64e100e532
commit 5c87325366
3 changed files with 36 additions and 23 deletions
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1
video_encoder/TAV_README.md
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@@ -9,6 +9,7 @@ TAV (TSVM Advanced Video) is a modern video codec built on discrete wavelet tran
### Key Advantages
- **No blocking artefacts**: Large-tile DWT encoding with padding eliminates DCT block boundaries
- **No colour banding**: Wavelets spreads gradients across scales, preventing banding in the first place
- **Perceptual optimisation**: HVS-aware quantisation preserves visual quality where it matters
- **Temporal coherence**: 3D DWT with GOP encoding exploits inter-frame similarity
- **Efficient sparse coding**: EZBC encoding exploits coefficient sparsity for 16-18% additional compression

57
video_encoder/encoder_tav.c
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@@ -18,7 +18,7 @@
#include <limits.h>
#include <float.h>
#define ENCODER_VENDOR_STRING "Encoder-TAV 20251113 (3d-dwt,tad,ssf-tc)"
#define ENCODER_VENDOR_STRING "Encoder-TAV 20251115 (3d-dwt,tad,ssf-tc)"
// TSVM Advanced Video (TAV) format constants
#define TAV_MAGIC "\x1F\x54\x53\x56\x4D\x54\x41\x56" // "\x1FTSVM TAV"
@@ -168,6 +168,8 @@ int debugDumpFrameTarget = -1; // -1 means disabled
typedef struct subtitle_entry {
int start_frame;
int end_frame;
uint64_t start_time_ns; // Direct timestamp in nanoseconds (for SSF-TC)
uint64_t end_time_ns; // Direct timestamp in nanoseconds (for SSF-TC)
char *text;
struct subtitle_entry *next;
} subtitle_entry_t;
@@ -7557,12 +7559,34 @@ static int srt_time_to_frame(const char *time_str, int fps) {
return (int)(total_seconds * fps + 0.5); // Round to nearest frame
}
// Convert SRT time format directly to nanoseconds (for SSF-TC timecode)
static uint64_t srt_time_to_ns(const char *time_str) {
int hours, minutes, seconds, milliseconds;
if (sscanf(time_str, "%d:%d:%d,%d", &hours, &minutes, &seconds, &milliseconds) != 4) {
return 0;
}
// Calculate total time in nanoseconds
uint64_t total_ns = 0;
total_ns += (uint64_t)hours * 3600ULL * 1000000000ULL; // hours to nanoseconds
total_ns += (uint64_t)minutes * 60ULL * 1000000000ULL; // minutes to nanoseconds
total_ns += (uint64_t)seconds * 1000000000ULL; // seconds to nanoseconds
total_ns += (uint64_t)milliseconds * 1000000ULL; // milliseconds to nanoseconds
return total_ns;
}
// Convert SAMI milliseconds to frame number
static int sami_ms_to_frame(int milliseconds, int fps) {
double seconds = milliseconds / 1000.0;
return (int)(seconds * fps + 0.5); // Round to nearest frame
}
// Convert SAMI milliseconds to nanoseconds (for SSF-TC timecode)
static uint64_t sami_ms_to_ns(int milliseconds) {
return (uint64_t)milliseconds * 1000000ULL;
}
// Parse SubRip subtitle file
static subtitle_entry_t* parse_srt_file(const char *filename, int fps) {
FILE *file = fopen(filename, "r");
@@ -7603,6 +7627,8 @@ static subtitle_entry_t* parse_srt_file(const char *filename, int fps) {
if (sscanf(line, "%31s --> %31s", start_time, end_time) == 2) {
current_entry->start_frame = srt_time_to_frame(start_time, fps);
current_entry->end_frame = srt_time_to_frame(end_time, fps);
current_entry->start_time_ns = srt_time_to_ns(start_time);
current_entry->end_time_ns = srt_time_to_ns(end_time);
if (current_entry->start_frame < 0 || current_entry->end_frame < 0) {
free(current_entry);
@@ -7903,6 +7929,7 @@ static subtitle_entry_t* parse_smi_file(const char *filename, int fps) {
subtitle_entry_t *entry = calloc(1, sizeof(subtitle_entry_t));
if (entry) {
entry->start_frame = sami_ms_to_frame(start_ms, fps);
entry->start_time_ns = sami_ms_to_ns(start_ms);
entry->text = strdup(start);
// Set end frame to next subtitle start or a default duration
@@ -7919,13 +7946,16 @@ static subtitle_entry_t* parse_smi_file(const char *filename, int fps) {
int next_ms = atoi(next_start);
if (next_ms > start_ms) {
entry->end_frame = sami_ms_to_frame(next_ms, fps);
entry->end_time_ns = sami_ms_to_ns(next_ms);
} else {
entry->end_frame = entry->start_frame + fps * 3; // 3 second default
entry->end_time_ns = entry->start_time_ns + 3000000000ULL; // 3 seconds in ns
}
}
}
} else {
entry->end_frame = entry->start_frame + fps * 3; // 3 second default
entry->end_time_ns = entry->start_time_ns + 3000000000ULL; // 3 seconds in ns
}
// Add to list
@@ -8733,31 +8763,12 @@ static int write_all_subtitles_tc(tav_encoder_t *enc, FILE *output) {
int bytes_written = 0;
int subtitle_count = 0;
// Convert frame timing to nanoseconds
// For NTSC: frame_time = 1001000000 / 30000 nanoseconds
// For others: frame_time = 1e9 / fps nanoseconds
uint64_t frame_time_ns;
if (enc->is_ntsc_framerate) {
frame_time_ns = 1001000000ULL / 30000ULL; // NTSC: 30000/1001 fps
} else {
frame_time_ns = (uint64_t)(1000000000.0 / enc->fps);
}
// Iterate through all subtitles and write them with timecodes
subtitle_entry_t *sub = enc->subtitles;
while (sub) {
// Calculate timecodes for show and hide events
uint64_t show_timecode;
uint64_t hide_timecode;
if (enc->is_ntsc_framerate) {
// NTSC: time = frame * 1001000000 / 30000
show_timecode = ((uint64_t)sub->start_frame * 1001000000ULL) / 30000ULL;
hide_timecode = ((uint64_t)sub->end_frame * 1001000000ULL) / 30000ULL;
} else {
show_timecode = (uint64_t)sub->start_frame * frame_time_ns;
hide_timecode = (uint64_t)sub->end_frame * frame_time_ns;
}
// Use direct nanosecond timestamps from SRT file (no frame conversion needed)
uint64_t show_timecode = sub->start_time_ns;
uint64_t hide_timecode = sub->end_time_ns;
// Write show subtitle event
bytes_written += write_subtitle_packet_tc(output, 0, 0x01, sub->text, show_timecode);

1
video_encoder/encoder_tev.c
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@@ -13,6 +13,7 @@
#include <ctype.h>
#include <sys/time.h>
#include <time.h>
#include <limits.h>
// TSVM Enhanced Video (TEV) format constants
#define TEV_MAGIC "\x1F\x54\x53\x56\x4D\x54\x45\x56" // "\x1FTSVM TEV"