[FFmpeg-devel] [PATCH v3] libavcodec/v4l2_buffers.c: set AVFrame interlaced flags

[James Almer]

On 12/18/2024 6:59 PM, Scott Theisen wrote:
> Originally from:
> https://github.com/MythTV/mythtv/commit/669955c6cb29196b4b5120451b5b998d67a65749
> 
> ---
> 
> v3:
> remove unnecessary clearing of already 0 valued flags
> use switch-case; I don't really think it is any simpler, but I do like the format better.
> ---
>   libavcodec/v4l2_buffers.c | 19 +++++++++++++++++++
>   1 file changed, 19 insertions(+)
> 
> diff --git a/libavcodec/v4l2_buffers.c b/libavcodec/v4l2_buffers.c
> index 23474ee143..19cc86334b 100644
> --- a/libavcodec/v4l2_buffers.c
> +++ b/libavcodec/v4l2_buffers.c
> @@ -210,6 +210,24 @@ static enum AVColorTransferCharacteristic v4l2_get_color_trc(V4L2Buffer *buf)
>       return AVCOL_TRC_UNSPECIFIED;
>   }
>   
> +static void v4l2_get_interlacing(AVFrame *frame, V4L2Buffer *buf)
> +{
> +    enum v4l2_field field;
> +    field = V4L2_TYPE_IS_MULTIPLANAR(buf->buf.type) ?
> +        buf->context->format.fmt.pix_mp.field :
> +        buf->context->format.fmt.pix.field;
> +
> +    switch (field) {
> +    case V4L2_FIELD_INTERLACED:
> +    case V4L2_FIELD_INTERLACED_TB:
> +        frame->flags |=  AV_FRAME_FLAG_TOP_FIELD_FIRST;
> +        /* fallthrough */
> +    case V4L2_FIELD_INTERLACED_BT:
> +        frame->flags |=  AV_FRAME_FLAG_INTERLACED;
> +        break;
> +    }
> +}
> +
>   static void v4l2_free_buffer(void *opaque, uint8_t *unused)
>   {
>       V4L2Buffer* avbuf = opaque;
> @@ -434,6 +452,7 @@ int ff_v4l2_buffer_buf_to_avframe(AVFrame *frame, V4L2Buffer *avbuf)
>       frame->color_trc = v4l2_get_color_trc(avbuf);
>       frame->pts = v4l2_get_pts(avbuf);
>       frame->pkt_dts = AV_NOPTS_VALUE;
> +    v4l2_get_interlacing(frame, avbuf);
>   
>       /* these values are updated also during re-init in v4l2_process_driver_event */
>       frame->height = avbuf->context->height;

Should be ok, but i don't maintain (nor can test) v4l2. So if nobody 
reviews it or pushes it in a few days, I'll.

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