Hi destal,
On Wed, 27 May 2026 06:20:36 +0000
destal takul wrote:
> Thank you for the clarification. Is there any way to fix the files that were
> remuxed with those warnings, or do I have to remux from the original? I have
> been using the Cygwin version of ffmpeg to cut the end of videos muxed with
> mkvmerge on non-key-frames since mkvmerge itself doesn't support this, and I
> probably have hundreds of files that have been remuxed with such warnings
> over the course of the past few years.
Sorry for inconvinience.
Could you please try attached tool? This should fix the broken
timestamp.
Usage: fix_ts broken.mkv output.mkv
To compile this, you need libavformat-devel, libavcodec-devel,
and libavutil-deve packages.
--
Takashi Yano <[email protected]>
#include <libavformat/avformat.h>
#include <libavcodec/avcodec.h>
#include <stdlib.h>
#include <string.h>
typedef struct {
int index;
int display_rank;
} FrameMap;
static int cmp_frame(const void *a, const void *b) {
return ((FrameMap*)a)->display_rank - ((FrameMap*)b)->display_rank;
}
#define MAX_REORDER_DELAY 16
void cleanup(AVFormatContext *ifmt, AVFormatContext *ofmt,
AVCodecParserContext *parser, AVCodecContext *codec_ctx,
FrameMap *map, FrameMap *sorted) {
if (parser) av_parser_close(parser);
if (codec_ctx) avcodec_free_context(&codec_ctx);
if (ifmt) avformat_close_input(&ifmt);
if (ofmt) {
if (!(ofmt->oformat->flags & AVFMT_NOFILE)) avio_closep(&ofmt->pb);
avformat_free_context(ofmt);
}
if (map) free(map);
if (sorted) free(sorted);
}
int main(int argc, char **argv) {
int ret = 1;
if (argc < 3) {
fprintf(stderr, "Usage: %s in.mkv out.mkv\n", argv[0]);
return 1;
}
AVFormatContext *ifmt = NULL, *ofmt = NULL;
AVCodecParserContext *parser = NULL;
AVCodecContext *codec_ctx = NULL;
FrameMap *map = NULL, *sorted = NULL;
int frame_count = 0, frame_cap = 10000;
if (avformat_open_input(&ifmt, argv[1], NULL, NULL) < 0) {
fprintf(stderr, "avformat_open_input() failed.\n");
goto end;
}
if (avformat_find_stream_info(ifmt, NULL) < 0) {
fprintf(stderr, "avformat_find_stream_info() failed.\n");
goto end;
}
int video_index = -1;
for (unsigned i = 0; i < ifmt->nb_streams; i++)
if (ifmt->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO)
video_index = i;
parser = av_parser_init(AV_CODEC_ID_H264);
codec_ctx = avcodec_alloc_context3(NULL);
avcodec_parameters_to_context(codec_ctx,
ifmt->streams[video_index]->codecpar);
map = malloc(frame_cap * sizeof(FrameMap));
AVPacket pkt;
uint64_t pict_num_msb = 0;
int prev_pict_num = -1;
while (av_read_frame(ifmt, &pkt) >= 0) {
if (pkt.stream_index == video_index) {
if (frame_count >= frame_cap) {
frame_cap *= 2;
map = realloc(map, frame_cap * sizeof(FrameMap));
}
uint8_t *data; int size;
av_parser_parse2(parser, codec_ctx, &data, &size,
pkt.data, pkt.size, AV_NOPTS_VALUE, AV_NOPTS_VALUE, 0);
if (prev_pict_num >= 0 &&
parser->output_picture_number - prev_pict_num
< -MAX_REORDER_DELAY)
pict_num_msb++;
map[frame_count] =
(FrameMap){frame_count, parser->output_picture_number
+ (int)(pict_num_msb * 1024)};
prev_pict_num = parser->output_picture_number;
frame_count++;
}
av_packet_unref(&pkt);
}
sorted = malloc(frame_count * sizeof(FrameMap));
memcpy(sorted, map, frame_count * sizeof(FrameMap));
qsort(sorted, frame_count, sizeof(FrameMap), cmp_frame);
for (int i = 0; i < frame_count; i++)
map[sorted[i].index].display_rank = i;
if (avformat_alloc_output_context2(&ofmt, NULL, NULL, argv[2]) != 0) {
fprintf(stderr, "avformat_alloc_output_context2() failed.\n");
goto end;
}
for (unsigned i = 0; i < ifmt->nb_streams; i++) {
AVStream *out_st = avformat_new_stream(ofmt, NULL);
avcodec_parameters_copy(out_st->codecpar, ifmt->streams[i]->codecpar);
}
AVStream *in_st = ifmt->streams[video_index];
if (!(ofmt->oformat->flags & AVFMT_NOFILE))
avio_open(&ofmt->pb, argv[2], AVIO_FLAG_WRITE);
if (avformat_write_header(ofmt, NULL) < 0) {
fprintf(stderr, "avformat_write_header() failed.\n");
goto end;
}
AVRational out_tb = ofmt->streams[video_index]->time_base;
AVRational frame_rate = in_st->avg_frame_rate;
if (frame_rate.num == 0)
frame_rate = in_st->r_frame_rate;
av_seek_frame(ifmt, video_index, 0, AVSEEK_FLAG_BACKWARD);
int current = 0;
while (av_read_frame(ifmt, &pkt) >= 0) {
if (pkt.stream_index == video_index) {
pkt.pts = av_rescale_q(map[current].display_rank,
av_inv_q(frame_rate), out_tb);
pkt.dts = av_rescale_q(current - MAX_REORDER_DELAY,
av_inv_q(frame_rate), out_tb);
pkt.duration = av_rescale_q(1, av_inv_q(frame_rate), out_tb);
current++;
}
if (ifmt->streams[pkt.stream_index]->codecpar->codec_type
== AVMEDIA_TYPE_AUDIO)
av_packet_rescale_ts(&pkt,
ifmt->streams[pkt.stream_index]->time_base,
ofmt->streams[pkt.stream_index]->time_base);
av_interleaved_write_frame(ofmt, &pkt);
av_packet_unref(&pkt);
}
av_write_trailer(ofmt);
ret = 0;
end:
cleanup(ifmt, ofmt, parser, codec_ctx, map, sorted);
return ret;
}
fix_ts: fix_ts.c
$(CC) $< -o $@ -lavformat -lavcodec -lavutil
clean:
$(RM) fix_ts
--
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