[FFmpeg-devel] [PATCH 1/2] libavcodec/v4l2_buffers.c: set AVFrame interlaced flags

[James Almer]

On 12/15/2024 1:14 AM, Scott Theisen wrote:
> Originally from:
> https://github.com/MythTV/mythtv/commit/669955c6cb29196b4b5120451b5b998d67a65749
> ---
>   libavcodec/v4l2_buffers.c | 38 ++++++++++++++++++++++++++++++++++++++
>   1 file changed, 38 insertions(+)
> 
> diff --git a/libavcodec/v4l2_buffers.c b/libavcodec/v4l2_buffers.c
> index 23474ee143..56a8f0825c 100644
> --- a/libavcodec/v4l2_buffers.c
> +++ b/libavcodec/v4l2_buffers.c
> @@ -210,6 +210,43 @@ 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;
> +
> +    if (field == V4L2_FIELD_INTERLACED || field == V4L2_FIELD_INTERLACED_TB) {
> +        frame->flags |=  AV_FRAME_FLAG_INTERLACED;
> +        frame->flags |=  AV_FRAME_FLAG_TOP_FIELD_FIRST;
> +#if FF_API_INTERLACED_FRAME
> +FF_DISABLE_DEPRECATION_WARNINGS
> +        frame->interlaced_frame = 1;
> +        frame->top_field_first  = 1;

No need to set these two fields. It's done by the generic code.

> +FF_ENABLE_DEPRECATION_WARNINGS
> +#endif
> +    } else if (field == V4L2_FIELD_INTERLACED_BT) {
> +        frame->flags |=  AV_FRAME_FLAG_INTERLACED;
> +        frame->flags &= ~AV_FRAME_FLAG_TOP_FIELD_FIRST;
> +#if FF_API_INTERLACED_FRAME
> +FF_DISABLE_DEPRECATION_WARNINGS
> +        frame->interlaced_frame = 1;
> +        frame->top_field_first  = 0;
> +FF_ENABLE_DEPRECATION_WARNINGS
> +#endif
> +    } else {
> +        frame->flags &= ~AV_FRAME_FLAG_INTERLACED;
> +        frame->flags &= ~AV_FRAME_FLAG_TOP_FIELD_FIRST;
> +#if FF_API_INTERLACED_FRAME
> +FF_DISABLE_DEPRECATION_WARNINGS
> +        frame->interlaced_frame = 0;
> +        frame->top_field_first  = 0;
> +FF_ENABLE_DEPRECATION_WARNINGS
> +#endif
> +    }
> +}
> +
>   static void v4l2_free_buffer(void *opaque, uint8_t *unused)
>   {
>       V4L2Buffer* avbuf = opaque;
> @@ -434,6 +471,7 @@ 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;

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