[FFmpeg-cvslog] ffmpeg: fix order between field order autodetection and override

[Jan Ekström]

ffmpeg | branch: release/4.4 | Jan Ekström <jeebjp at gmail.com> | Mon Jul 19 23:25:28 2021 +0300| [926d8b844fee222cb68dfd393273d7876a84e088] | committer: Jan Ekström

ffmpeg: fix order between field order autodetection and override

Having the override before autodetection meant that the overridden
value got overwritten by the autodetected result each time,
effectively disabling the ability to utilize the `-top` option
for override purposes.

Somehow I missed this in fbb44bc51a647862eb05ae3f9d7d49a0be9bed57 ,
even though the lines were within the context. Probably the code
originally being after this logic had something to do with it,
but previously it only touched the avformat context's codecpar,
which did not affect the encoder codec context whatsoever.

Fixes #9320
Fixes #9339

(cherry picked from commit 4c694093be68d401c60819e5171817c62afef8b2)

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=926d8b844fee222cb68dfd393273d7876a84e088
---

 fftools/ffmpeg.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/fftools/ffmpeg.c b/fftools/ffmpeg.c
index 7d533c3806..9a34d1f13e 100644
--- a/fftools/ffmpeg.c
+++ b/fftools/ffmpeg.c
@@ -3463,12 +3463,7 @@ static int init_output_stream_encode(OutputStream *ost, AVFrame *frame)
             enc_ctx->bits_per_raw_sample = frame_bits_per_raw_sample;
         }
 
-        if (ost->top_field_first == 0) {
-            enc_ctx->field_order = AV_FIELD_BB;
-        } else if (ost->top_field_first == 1) {
-            enc_ctx->field_order = AV_FIELD_TT;
-        }
-
+        // Field order: autodetection
         if (frame) {
             if (enc_ctx->flags & (AV_CODEC_FLAG_INTERLACED_DCT | AV_CODEC_FLAG_INTERLACED_ME) &&
                 ost->top_field_first >= 0)
@@ -3483,6 +3478,13 @@ static int init_output_stream_encode(OutputStream *ost, AVFrame *frame)
                 enc_ctx->field_order = AV_FIELD_PROGRESSIVE;
         }
 
+        // Field order: override
+        if (ost->top_field_first == 0) {
+            enc_ctx->field_order = AV_FIELD_BB;
+        } else if (ost->top_field_first == 1) {
+            enc_ctx->field_order = AV_FIELD_TT;
+        }
+
         if (ost->forced_keyframes) {
             if (!strncmp(ost->forced_keyframes, "expr:", 5)) {
                 ret = av_expr_parse(&ost->forced_keyframes_pexpr, ost->forced_keyframes+5,