[FFmpeg-devel] [PATCH] libavformat/concatdev.c: use the unified time base

[FFmpeg-devel] [PATCH] libavformat/concatdev.c: use the unified time base

[Ye Chuan]

In some case, the input files have different time base
even though they  share the same codec and codec parameters,

So when we replace the packet, we need use the unified time base
instead of it of each stream own, which may lead to wrong pts/dts
of the output packet.

Signed-off-by: Chuan Ye <yechuan0102@hotmail.com>
---
libavformat/concatdec.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/libavformat/concatdec.c b/libavformat/concatdec.c
index 0603c6e254..f7067d5059 100644
--- a/libavformat/concatdec.c
+++ b/libavformat/concatdec.c
@@ -740,6 +740,7 @@ static int concat_read_packet(AVFormatContext *avf, AVPacket *pkt)
    ConcatStream *cs;
    AVStream *st;
    FFStream *sti;
+    AVRational output_tb;

    if (cat->eof)
        return AVERROR_EOF;
@@ -782,13 +783,15 @@ static int concat_read_packet(AVFormatContext *avf, AVPacket *pkt)
           av_ts2str(pkt->pts), av_ts2timestr(pkt->pts, &st->time_base),
           av_ts2str(pkt->dts), av_ts2timestr(pkt->dts, &st->time_base));

+    /* replace the pkt base on the time base of target output stream */
+    output_tb = avf->streams[cs->out_stream_index]->time_base;
    delta = av_rescale_q(cat->cur_file->start_time - cat->cur_file->file_inpoint,
                         AV_TIME_BASE_Q,
-                         cat->avf->streams[pkt->stream_index]->time_base);
+                         output_tb);
    if (pkt->pts != AV_NOPTS_VALUE)
-        pkt->pts += delta;
+        pkt->pts = av_rescale_q(pkt->pts, st->time_base, output_tb) + delta;
    if (pkt->dts != AV_NOPTS_VALUE)
-        pkt->dts += delta;
+        pkt->dts = av_rescale_q(pkt->dts, st->time_base, output_tb) + delta;
    av_log(avf, AV_LOG_DEBUG, " -> pts:%s pts_time:%s dts:%s dts_time:%s\n",
           av_ts2str(pkt->pts), av_ts2timestr(pkt->pts, &st->time_base),
           av_ts2str(pkt->dts), av_ts2timestr(pkt->dts, &st->time_base));
-- 
2.30.1

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Re: [FFmpeg-devel] [PATCH] libavformat/concatdev.c: use the unified time base

[Gyan Doshi]

On 2022-03-01 09:46 am, Ye Chuan wrote:
> In some case, the input files have different time base
> even though they  share the same codec and codec parameters,
>
> So when we replace the packet, we need use the unified time base
> instead of it of each stream own, which may lead to wrong pts/dts
> of the output packet.
Make this optional. This 'bug' has been used to effect speed change in 
some inputs.

Regards,
Gyan

>
> Signed-off-by: Chuan Ye <yechuan0102@hotmail.com>
> ---
> libavformat/concatdec.c | 9 ++++++---
> 1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/libavformat/concatdec.c b/libavformat/concatdec.c
> index 0603c6e254..f7067d5059 100644
> --- a/libavformat/concatdec.c
> +++ b/libavformat/concatdec.c
> @@ -740,6 +740,7 @@ static int concat_read_packet(AVFormatContext *avf, AVPacket *pkt)
>      ConcatStream *cs;
>      AVStream *st;
>      FFStream *sti;
> +    AVRational output_tb;
>
>      if (cat->eof)
>          return AVERROR_EOF;
> @@ -782,13 +783,15 @@ static int concat_read_packet(AVFormatContext *avf, AVPacket *pkt)
>             av_ts2str(pkt->pts), av_ts2timestr(pkt->pts, &st->time_base),
>             av_ts2str(pkt->dts), av_ts2timestr(pkt->dts, &st->time_base));
>
> +    /* replace the pkt base on the time base of target output stream */
> +    output_tb = avf->streams[cs->out_stream_index]->time_base;
>      delta = av_rescale_q(cat->cur_file->start_time - cat->cur_file->file_inpoint,
>                           AV_TIME_BASE_Q,
> -                         cat->avf->streams[pkt->stream_index]->time_base);
> +                         output_tb);
>      if (pkt->pts != AV_NOPTS_VALUE)
> -        pkt->pts += delta;
> +        pkt->pts = av_rescale_q(pkt->pts, st->time_base, output_tb) + delta;
>      if (pkt->dts != AV_NOPTS_VALUE)
> -        pkt->dts += delta;
> +        pkt->dts = av_rescale_q(pkt->dts, st->time_base, output_tb) + delta;
>      av_log(avf, AV_LOG_DEBUG, " -> pts:%s pts_time:%s dts:%s dts_time:%s\n",
>             av_ts2str(pkt->pts), av_ts2timestr(pkt->pts, &st->time_base),
>             av_ts2str(pkt->dts), av_ts2timestr(pkt->dts, &st->time_base));

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Re: [FFmpeg-devel] [PATCH] libavformat/concatdev.c: use the unified time base

[Ye Chuan]

Hi Gyan

Thanks for suggestion

Base on the different  time_base, the connection between the streams, the pts and dts may be not continuate, the the codec
May reporte warning. Is that ‘bug’ acceptable?

Regards,

Chuan Ye

From: ffmpeg-devel <ffmpeg-devel-bounces@ffmpeg.org> on behalf of Gyan Doshi <ffmpeg@gyani.pro>
Date: Tuesday, March 1, 2022 at 12:49 PM
To: ffmpeg-devel@ffmpeg.org <ffmpeg-devel@ffmpeg.org>
Subject: Re: [FFmpeg-devel] [PATCH] libavformat/concatdev.c: use the unified time base


On 2022-03-01 09:46 am, Ye Chuan wrote:
> In some case, the input files have different time base
> even though they  share the same codec and codec parameters,
>
> So when we replace the packet, we need use the unified time base
> instead of it of each stream own, which may lead to wrong pts/dts
> of the output packet.
Make this optional. This 'bug' has been used to effect speed change in
some inputs.

Regards,
Gyan

>
> Signed-off-by: Chuan Ye <yechuan0102@hotmail.com>
> ---
> libavformat/concatdec.c | 9 ++++++---
> 1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/libavformat/concatdec.c b/libavformat/concatdec.c
> index 0603c6e254..f7067d5059 100644
> --- a/libavformat/concatdec.c
> +++ b/libavformat/concatdec.c
> @@ -740,6 +740,7 @@ static int concat_read_packet(AVFormatContext *avf, AVPacket *pkt)
>      ConcatStream *cs;
>      AVStream *st;
>      FFStream *sti;
> +    AVRational output_tb;
>
>      if (cat->eof)
>          return AVERROR_EOF;
> @@ -782,13 +783,15 @@ static int concat_read_packet(AVFormatContext *avf, AVPacket *pkt)
>             av_ts2str(pkt->pts), av_ts2timestr(pkt->pts, &st->time_base),
>             av_ts2str(pkt->dts), av_ts2timestr(pkt->dts, &st->time_base));
>
> +    /* replace the pkt base on the time base of target output stream */
> +    output_tb = avf->streams[cs->out_stream_index]->time_base;
>      delta = av_rescale_q(cat->cur_file->start_time - cat->cur_file->file_inpoint,
>                           AV_TIME_BASE_Q,
> -                         cat->avf->streams[pkt->stream_index]->time_base);
> +                         output_tb);
>      if (pkt->pts != AV_NOPTS_VALUE)
> -        pkt->pts += delta;
> +        pkt->pts = av_rescale_q(pkt->pts, st->time_base, output_tb) + delta;
>      if (pkt->dts != AV_NOPTS_VALUE)
> -        pkt->dts += delta;
> +        pkt->dts = av_rescale_q(pkt->dts, st->time_base, output_tb) + delta;
>      av_log(avf, AV_LOG_DEBUG, " -> pts:%s pts_time:%s dts:%s dts_time:%s\n",
>             av_ts2str(pkt->pts), av_ts2timestr(pkt->pts, &st->time_base),
>             av_ts2str(pkt->dts), av_ts2timestr(pkt->dts, &st->time_base));

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[FFmpeg-devel] [PATCH] libavformat/concatdev.c use the unified time base

[Ye Chuan]

in some case, the input files have different time base
even though they  share the same codec and codec parameters,

so when we replace the packet, we need use the unified time base
instead of it of each stream own, which may lead to wrong pts/dts
of the output packet.

Signed-off-by: Chuan Ye <yechuan0102@hotmail.com<mailto:yechuan0102@hotmail.com>>
---
libavformat/concatdec.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/libavformat/concatdec.c b/libavformat/concatdec.c
index 0603c6e254..f7067d5059 100644
--- a/libavformat/concatdec.c
+++ b/libavformat/concatdec.c
@@ -740,6 +740,7 @@ static int concat_read_packet(AVFormatContext *avf, AVPacket *pkt)
     ConcatStream *cs;
     AVStream *st;
     FFStream *sti;
+    AVRational output_tb;

     if (cat->eof)
         return AVERROR_EOF;
@@ -782,13 +783,15 @@ static int concat_read_packet(AVFormatContext *avf, AVPacket *pkt)
            av_ts2str(pkt->pts), av_ts2timestr(pkt->pts, &st->time_base),
            av_ts2str(pkt->dts), av_ts2timestr(pkt->dts, &st->time_base));

+    /* replace the pkt base on the time base of target output stream */
+    output_tb = avf->streams[cs->out_stream_index]->time_base;
     delta = av_rescale_q(cat->cur_file->start_time - cat->cur_file->file_inpoint,
                          AV_TIME_BASE_Q,
-                         cat->avf->streams[pkt->stream_index]->time_base);
+                         output_tb);
     if (pkt->pts != AV_NOPTS_VALUE)
-        pkt->pts += delta;
+        pkt->pts = av_rescale_q(pkt->pts, st->time_base, output_tb) + delta;
     if (pkt->dts != AV_NOPTS_VALUE)
-        pkt->dts += delta;
+        pkt->dts = av_rescale_q(pkt->dts, st->time_base, output_tb) + delta;
     av_log(avf, AV_LOG_DEBUG, " -> pts:%s pts_time:%s dts:%s dts_time:%s\n",
            av_ts2str(pkt->pts), av_ts2timestr(pkt->pts, &st->time_base),
            av_ts2str(pkt->dts), av_ts2timestr(pkt->dts, &st->time_base));
--
2.30.1 (Apple Git-130)



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