[FFmpeg-devel] [PATCH] avcodec/gif: fix duration of last packet/frame

[Paul B Mahol]

Hi,

patch attached.

From f126c6ef9e5fa8b51272508af6603f05c26a3f26 Mon Sep 17 00:00:00 2001
From: Paul B Mahol <one...@gmail.com>
Date: Tue, 23 Aug 2022 11:51:24 +0200
Subject: [PATCH] avcodec/gif: fix duration of last packet/frame

Fixes #6294

Signed-off-by: Paul B Mahol <one...@gmail.com>
---
 libavcodec/gif.c  |  2 ++
 libavformat/gif.c | 33 +++++++--------------------------
 2 files changed, 9 insertions(+), 26 deletions(-)

diff --git a/libavcodec/gif.c b/libavcodec/gif.c
index 8e84b79b8c..2484cc92e2 100644
--- a/libavcodec/gif.c
+++ b/libavcodec/gif.c
@@ -513,6 +513,8 @@ static int gif_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
             return ret;
     }
 
+    pkt->duration = av_rescale_q(pict->duration, (AVRational){ 1, 100 },
+                                 avctx->time_base);
     pkt->size   = outbuf_ptr - pkt->data;
     if (s->image || !avctx->frame_number)
         pkt->flags |= AV_PKT_FLAG_KEY;
diff --git a/libavformat/gif.c b/libavformat/gif.c
index b52ff4dd39..afb5767541 100644
--- a/libavformat/gif.c
+++ b/libavformat/gif.c
@@ -36,7 +36,6 @@ typedef struct GIFContext {
     int duration;
     int64_t last_pos;
     int have_end;
-    AVPacket *prev_pkt;
 } GIFContext;
 
 static int gif_write_header(AVFormatContext *s)
@@ -81,28 +80,20 @@ static int gif_parse_packet(AVFormatContext *s, const uint8_t *data, int size)
     return 0;
 }
 
-static int gif_get_delay(GIFContext *gif, AVPacket *prev, AVPacket *new)
+static int gif_get_delay(GIFContext *gif, AVPacket *pkt)
 {
-    if (new && new->pts != AV_NOPTS_VALUE)
-        gif->duration = av_clip_uint16(new->pts - prev->pts);
-    else if (!new && gif->last_delay >= 0)
+    if (pkt->duration != 0)
+        gif->duration = av_clip_uint16(pkt->duration);
+    else if (!pkt && gif->last_delay >= 0)
         gif->duration = gif->last_delay;
 
     return gif->duration;
 }
 
-static int gif_write_packet(AVFormatContext *s, AVPacket *new_pkt)
+static int gif_write_packet(AVFormatContext *s, AVPacket *pkt)
 {
     GIFContext *gif = s->priv_data;
     AVIOContext *pb = s->pb;
-    AVPacket *pkt = gif->prev_pkt;
-
-    if (!gif->prev_pkt) {
-        gif->prev_pkt = av_packet_alloc();
-        if (!gif->prev_pkt)
-            return AVERROR(ENOMEM);
-        return av_packet_ref(gif->prev_pkt, new_pkt);
-    }
 
     gif->last_pos = avio_tell(pb);
     if (pkt->size > 0)
@@ -144,7 +135,7 @@ static int gif_write_packet(AVFormatContext *s, AVPacket *new_pkt)
         delay_pos = gif_parse_packet(s, pkt->data + off, pkt->size - off);
         if (delay_pos > 0 && delay_pos < pkt->size - off - 2) {
             avio_write(pb, pkt->data + off, delay_pos);
-            avio_wl16(pb, gif_get_delay(gif, pkt, new_pkt));
+            avio_wl16(pb, gif_get_delay(gif, pkt));
             avio_write(pb, pkt->data + off + delay_pos + 2, pkt->size - off - delay_pos - 2);
         } else {
             avio_write(pb, pkt->data + off, pkt->size - off);
@@ -154,17 +145,13 @@ static int gif_write_packet(AVFormatContext *s, AVPacket *new_pkt)
 
         if (delay_pos > 0 && delay_pos < pkt->size - 2) {
             avio_write(pb, pkt->data, delay_pos);
-            avio_wl16(pb, gif_get_delay(gif, pkt, new_pkt));
+            avio_wl16(pb, gif_get_delay(gif, pkt));
             avio_write(pb, pkt->data + delay_pos + 2, pkt->size - delay_pos - 2);
         } else {
             avio_write(pb, pkt->data, pkt->size);
         }
     }
 
-    av_packet_unref(gif->prev_pkt);
-    if (new_pkt)
-        return av_packet_ref(gif->prev_pkt, new_pkt);
-
     return 0;
 }
 
@@ -173,14 +160,8 @@ static int gif_write_trailer(AVFormatContext *s)
     GIFContext *gif = s->priv_data;
     AVIOContext *pb = s->pb;
 
-    if (!gif->prev_pkt)
-        return AVERROR(EINVAL);
-
-    gif_write_packet(s, NULL);
-
     if (!gif->have_end)
         avio_w8(pb, GIF_TRAILER);
-    av_packet_free(&gif->prev_pkt);
 
     return 0;
 }
-- 
2.37.2


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