fix(encoder): timestamp errors processing frames with PTS equal to 0

Signed-off-by: k4yt3x <i@k4yt3x.com>

CHANGELOG.md

@@ -5,6 +5,12 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [Unreleased]
+
+### Fixed
+
+- Timestamp errors processing frames with PTS equal to 0 (#1222).
+
 ## [6.1.1] - 2024-11-07
 
 ### Added

include/libvideo2x/encoder.h

@@ -28,7 +28,8 @@ int write_frame(
     AVFrame *frame,
     AVCodecContext *enc_ctx,
     AVFormatContext *ofmt_ctx,
-    int out_vstream_idx
+    int out_vstream_idx,
+    int64_t frame_idx
 );
 
 int flush_encoder(AVCodecContext *enc_ctx, AVFormatContext *ofmt_ctx, int out_vstream_idx);

src/encoder.cpp

@@ -3,6 +3,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <cstdint>
 
 #include <spdlog/spdlog.h>
 
@@ -202,11 +203,17 @@ int write_frame(
     AVFrame *frame,
     AVCodecContext *enc_ctx,
     AVFormatContext *ofmt_ctx,
-    int out_vstream_idx
+    int out_vstream_idx,
+    int64_t frame_idx
 ) {
     AVFrame *converted_frame = nullptr;
     int ret;
 
+    // Set the frame's presentation timestamp if not set
+    if (frame->pts <= 0) {
+        frame->pts = frame_idx;
+    }
+
     // Convert the frame to the encoder's pixel format if needed
     if (frame->format != enc_ctx->pix_fmt) {
         converted_frame = convert_avframe_pix_fmt(frame, enc_ctx->pix_fmt);

src/libvideo2x.cpp

@@ -124,7 +124,13 @@ static int process_frames(
                     return ret;
                 } else if (ret == 0 && processed_frame != nullptr) {
                     if (!benchmark) {
-                        ret = write_frame(processed_frame, enc_ctx, ofmt_ctx, out_vstream_idx);
+                        ret = write_frame(
+                            processed_frame,
+                            enc_ctx,
+                            ofmt_ctx,
+                            out_vstream_idx,
+                            proc_ctx->processed_frames
+                        );
                         if (ret < 0) {
                             av_strerror(ret, errbuf, sizeof(errbuf));
                             spdlog::critical("Error encoding/writing frame: {}", errbuf);
@@ -174,7 +180,9 @@ static int process_frames(
 
     // Encode and write all flushed frames
     for (AVFrame *&flushed_frame : flushed_frames) {
-        ret = write_frame(flushed_frame, enc_ctx, ofmt_ctx, out_vstream_idx);
+        ret = write_frame(
+            flushed_frame, enc_ctx, ofmt_ctx, out_vstream_idx, proc_ctx->processed_frames
+        );
         if (ret < 0) {
             av_strerror(ret, errbuf, sizeof(errbuf));
             spdlog::critical("Error encoding/writing flushed frame: {}", errbuf);