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

[Zhao Zhili]

> On Dec 19, 2024, at 08:28, James Almer <jamrial at gmail.com> wrote:
> 
> 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.

I’m planing to do some test, maybe this weekend.

> 
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