[FFmpeg-devel] [PATCH v2 1/2] avcodec/v4l2_context: don't reinit output queue when dynamic resolution change

[Ming Qian]

in the v4l2 stateful video document, we can see the following
description:
    During the resolution change sequence, the OUTPUT queue must remain
    streaming. Calling VIDIOC_STREAMOFF() on the OUTPUT queue would
    abort the sequence and initiate a seek.

    In principle, the OUTPUT queue operates separately from the CAPTURE
    queue and this remains true for the duration of the entire
    resolution change sequence as well.

so don't reinit the output queue when handling the resolution change
event

Signed-off-by: Ming Qian <ming.qian at nxp.com>
---
 libavcodec/v4l2_context.c | 27 ++-------------------------
 1 file changed, 2 insertions(+), 25 deletions(-)

diff --git a/libavcodec/v4l2_context.c b/libavcodec/v4l2_context.c
index ff1ea8e57b08..dda5157698c3 100644
--- a/libavcodec/v4l2_context.c
+++ b/libavcodec/v4l2_context.c
@@ -162,9 +162,8 @@ static int v4l2_handle_event(V4L2Context *ctx)
 {
     V4L2m2mContext *s = ctx_to_m2mctx(ctx);
     struct v4l2_format cap_fmt = s->capture.format;
-    struct v4l2_format out_fmt = s->output.format;
     struct v4l2_event evt = { 0 };
-    int full_reinit, reinit, ret;
+    int reinit, ret;
 
     ret = ioctl(s->fd, VIDIOC_DQEVENT, &evt);
     if (ret < 0) {
@@ -180,25 +179,12 @@ static int v4l2_handle_event(V4L2Context *ctx)
     if (evt.type != V4L2_EVENT_SOURCE_CHANGE)
         return 0;
 
-    ret = ioctl(s->fd, VIDIOC_G_FMT, &out_fmt);
-    if (ret) {
-        av_log(logger(ctx), AV_LOG_ERROR, "%s VIDIOC_G_FMT\n", s->output.name);
-        return 0;
-    }
-
     ret = ioctl(s->fd, VIDIOC_G_FMT, &cap_fmt);
     if (ret) {
         av_log(logger(ctx), AV_LOG_ERROR, "%s VIDIOC_G_FMT\n", s->capture.name);
         return 0;
     }
 
-    full_reinit = v4l2_resolution_changed(&s->output, &out_fmt);
-    if (full_reinit) {
-        s->output.height = v4l2_get_height(&out_fmt);
-        s->output.width = v4l2_get_width(&out_fmt);
-        s->output.sample_aspect_ratio = v4l2_get_sar(&s->output);
-    }
-
     reinit = v4l2_resolution_changed(&s->capture, &cap_fmt);
     if (reinit) {
         s->capture.height = v4l2_get_height(&cap_fmt);
@@ -206,18 +192,9 @@ static int v4l2_handle_event(V4L2Context *ctx)
         s->capture.sample_aspect_ratio = v4l2_get_sar(&s->capture);
     }
 
-    if (full_reinit || reinit)
+    if (reinit)
         s->reinit = 1;
 
-    if (full_reinit) {
-        ret = ff_v4l2_m2m_codec_full_reinit(s);
-        if (ret) {
-            av_log(logger(ctx), AV_LOG_ERROR, "v4l2_m2m_codec_full_reinit\n");
-            return AVERROR(EINVAL);
-        }
-        goto reinit_run;
-    }
-
     if (reinit) {
         if (s->avctx)
             ret = ff_set_dimensions(s->avctx, s->capture.width, s->capture.height);
-- 
2.32.0