[FFmpeg-cvslog] Revert "avcodec/nvenc: fix b-frame DTS behavior with fractional framerates"

[Timo Rothenpieler]

ffmpeg | branch: release/6.0 | Timo Rothenpieler <timo at rothenpieler.org> | Thu Jun 15 00:45:44 2023 +0200| [cb3453eb25e249b7c428badd24d8dbcfc74ec3e7] | committer: Timo Rothenpieler

Revert "avcodec/nvenc: fix b-frame DTS behavior with fractional framerates"

This reverts commit 9a245bdf5d7860b8bc5e5c21a105a075925b719a.

This commit basically broke all samples with fractional framerates,
rather than fixing them.
I at this point do not understand the original issue anymore, and I'm
not sure how this slipped my initial testing.
All my test samples must have happened to have a simple timebase.

The actual dts values pretty much always are just a simple chain of
1,2,3,4,5,... Or maybe slightly bigger steps. Each increase by one means
an advance in time by one unit of the timebase.
So a fractional framerate/timebase is already not an issue.

So with this patch applied, the calculation might end up substracting
huge values (1001 is a common one) from the dts, which would be an
offset of that many frames, not of that many fractions of a second.
This broke at least muxing into mp4, if the sample happened to have a
fractional framerate.

I do not thing the original issue this patch tried to fix existed in the
first place, so it can be reverted without further consequences.

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=cb3453eb25e249b7c428badd24d8dbcfc74ec3e7
---

 libavcodec/nvenc.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/libavcodec/nvenc.c b/libavcodec/nvenc.c
index 50a4fa6f69..9acf3e8697 100644
--- a/libavcodec/nvenc.c
+++ b/libavcodec/nvenc.c
@@ -2266,8 +2266,7 @@ static int nvenc_set_timestamp(AVCodecContext *avctx,
     dts = reorder_queue_dequeue(ctx->reorder_queue, avctx, pkt);
 
     if (avctx->codec_descriptor->props & AV_CODEC_PROP_REORDER) {
-        pkt->dts = dts -
-            FFMAX(ctx->encode_config.frameIntervalP - 1, 0) * FFMAX(avctx->ticks_per_frame, 1) * FFMAX(avctx->time_base.num, 1);
+        pkt->dts = dts - FFMAX(ctx->encode_config.frameIntervalP - 1, 0) * FFMAX(avctx->ticks_per_frame, 1);
     } else {
         pkt->dts = pkt->pts;
     }