On 27/08/17 20:41, Jorge Ramirez wrote:
> On 08/27/2017 09:09 PM, Jorge Ramirez wrote:
>> On 08/25/2017 05:35 PM, wm4 wrote:
>>>> +static int buffer_ops_v4l2buf_to_avframe(AVFrame *frame, V4L2Buffer
>>>> *avbuf)
>>>> +{
>>>> + int i, ret;
>>>> +
>>>> + av_frame_unref(frame);
>>>> +
>>>> + /* 1. get references to the actual data */
>>>> + for (i = 0; i < avbuf->num_planes; i++) {
>>>> + ret = avbuf->ops.buf_to_bufref(avbuf, i, &frame->buf[i]);
>>>> + if (ret)
>>>> + return ret;
>>>> +
>>>> + frame->linesize[i] = avbuf->bytesperline[i];
>>>> + frame->data[i] = frame->buf[i]->data;
>>>> + }
>>>> +
>>>> + /* 1.1 fixup special cases */
>>>> + switch (avbuf->context->av_pix_fmt) {
>>>> + case AV_PIX_FMT_NV12:
>>>> + if (avbuf->num_planes > 1)
>>>> + break;
>>>> + frame->linesize[1] = avbuf->bytesperline[0];
>>>> + frame->data[1] = frame->buf[0]->data + avbuf->bytesperline[0] *
>>>> avbuf->context->format.fmt.pix_mp.height;
>>>> + break;
>>>> + default:
>>>> + break;
>>>> + }
>>>> +
>>>> + /* 2. get frame information */
>>>> + frame->key_frame = !!(avbuf->buf.flags & V4L2_BUF_FLAG_KEYFRAME);
>>>> + frame->format = avbuf->context->av_pix_fmt;
>>>> +
>>>> + /* these values are updated also during re-init in
>>>> process_video_event */
>>>> + frame->height = avbuf->context->height;
>>>> + frame->width = avbuf->context->width;
>>>> + frame->pts = get_pts(avbuf);
>>>> +
>>>> + /* 3. report errors upstream */
>>>> + if (avbuf->buf.flags & V4L2_BUF_FLAG_ERROR) {
>>>> + av_log(avbuf->context->log_ctx, AV_LOG_ERROR, "%s: driver decode
>>>> error\n", avbuf->context->name);
>>>> + frame->decode_error_flags |= FF_DECODE_ERROR_INVALID_BITSTREAM;
>>>> + }
>>>> +
>>>> + return 0;
>>>> +}
>>> This function seems to lack setting typically required metadata like
>>> colorspace.
>>>
>>
>> ok I will retrieve the colorspace from the v4l2 format structure and set it
>> in the frame.
>
> um, I dont see a 1:1 mapping between the colorspaces reported from v4l2 and
> what ffmpeg expects (I am also not a subject matter expert on this :( ).
>
> Could I get some guidance on the translation table below please?
> btw in my simple tests - ffplay decoded vp8, vp9, mpeg4, mpeg2, h263, h264
> and hevc I didnt need this field so I am not sure if I am getting it right.
>
> TIA
>
> static inline enum AVColorSpace get_colorspace(V4L2Buffer *buf)
> {
> enum v4l2_colorspace cs;
>
> cs = V4L2_TYPE_IS_MULTIPLANAR(buf->context->type) ?
> buf->context->format.fmt.pix_mp.colorspace :
> buf->context->format.fmt.pix.colorspace;
>
> /* */
> switch (cs) {
> case V4L2_COLORSPACE_SMPTE170M: return AVCOL_SPC_SMPTE170M;
> case V4L2_COLORSPACE_SMPTE240M: return AVCOL_SPC_SMPTE240M;
> case V4L2_COLORSPACE_470_SYSTEM_BG: return AVCOL_SPC_BT470BG;
> case V4L2_COLORSPACE_BT2020: return AVCOL_SPC_BT2020_CL;
> case V4L2_COLORSPACE_REC709: return AVCOL_SPC_BT709;
> case V4L2_COLORSPACE_ADOBERGB:
> case V4L2_COLORSPACE_SRGB:
> case V4L2_COLORSPACE_DCI_P3:
> case V4L2_COLORSPACE_JPEG:
> case V4L2_COLORSPACE_RAW:
> default:
> return AVCOL_SPC_RGB;
> }
> }
The ffmpeg enums use the same ISO 11664-1 values as H.264, H.265 and MPEG-2 do.
Since there must be code in your V4L2 driver to translate the V4L2 enums both
to and from that (for encode and decode respectively), I suggest just copying
the logic of that code to do the matching opposite direction on the ffmpeg
side. (Look for code reading/writing colour_primaries,
transfer_characteristics and matrix_coefficients in the VUI section of the SPS.)
- Mark
_______________________________________________
ffmpeg-devel mailing list
ffmpeg-devel@ffmpeg.org
http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
