On 2021-01-17 09:02, wrote Stephen Hutchinson:
Going into detail about GetParity wouldn't be necessary if it's not
used (and there aren't any other invoke-parsed functions aside from
checking with Import() whether the script actually returns a clip),
so the comment could be shortened. Also, since this is the avisynth
demuxer, 'in the avs' would be better rendered as 'in the script',
and simply refer to 'source plugins' rather than 'avisynth source
plugins'.
Comment bikeshedding aside, LGTM, but the avs_is* API usage added here
needs to be reflected in the AVSC_DECLARE_FUNC and LOAD_AVS_FUNC
blocks.
If those parts of the API are present in 2.5, the LOAD_AVS_FUNC can be
a
0. If they were added in 2.6 (or Plus, but I know these would have to
be
from classic AviSynth), then it should be 1.
Thanks for the very quick reply, i shortened the comment but as the
whole comment is basically just there to explain why i decided to not
involve getparity, i believe it is worth to mention in order to save
some time for possible future committers.
What i am not able to do is to add the used convenience functions
avs_is_tff and bff to AVSC_DECLARE_FUNC and LOAD_AVS_FUNC, it refuses to
compile when i do so. IMHO this is because it is just convenience
functions that's function body is defined in the linked avisynth_c.h
file instead of being exported by the avisynth api lib.
The existing code in avisynth.c also uses such convenience functions
without adding them to the declaration, examples:
avs_has_video, line 524
avs_is_clip, line 571
Also, i found it safe to use the convenience functions avs_is_tff and
bff because the minimum required version is 2.6 and Plus or above, so i
hoped the functions will be always available.From 0725b04b8855723309662a9b663b346d98117ff1 Mon Sep 17 00:00:00 2001
From: emcodem <emco...@ffastrans.com>
Date: Sun, 17 Jan 2021 18:59:41 +0100
Subject: [PATCH] Populate field order returned by avs script, Trac Ticket 8757
---
libavformat/avisynth.c | 15 +++++++++++++++
1 file changed, 15 insertions(+)
diff --git a/libavformat/avisynth.c b/libavformat/avisynth.c
index 2c08ace8db..75c7b18c22 100644
--- a/libavformat/avisynth.c
+++ b/libavformat/avisynth.c
@@ -241,6 +241,21 @@ static int avisynth_create_stream_video(AVFormatContext *s, AVStream *st)
st->nb_frames = avs->vi->num_frames;
avpriv_set_pts_info(st, 32, avs->vi->fps_denominator, avs->vi->fps_numerator);
+ av_log(s, AV_LOG_TRACE, "avs_is_field_based: %d\n", avs_is_field_based(avs->vi));
+ av_log(s, AV_LOG_TRACE, "avs_is_parity_known: %d\n", avs_is_parity_known(avs->vi));
+
+ /* The following typically only works when assumetff (-bff) and assumefieldbased is used in the source avs script.
+ Additional logic using GetParity() could deliver more accurate results but also decodes a frame which we want to avoid. */
+ st->codecpar->field_order = AV_FIELD_UNKNOWN;
+ if (avs_is_field_based(avs->vi)) {
+ if (avs_is_tff(avs->vi)) {
+ st->codecpar->field_order = AV_FIELD_TT;
+ }
+ else if (avs_is_bff(avs->vi)) {
+ st->codecpar->field_order = AV_FIELD_BB;
+ }
+ }
+
switch (avs->vi->pixel_type) {
/* 10~16-bit YUV pix_fmts (AviSynth+) */
case AVS_CS_YUV444P10:
--
2.25.1
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