FFMPEG RGB to YUV420P : Warning: data is not aligned! This can lead to a speedloss [duplicate] - ffmpeg

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Pixel format conversion issue [FFMPEG]
(2 answers)
Closed 4 years ago.
I am trying to convert a standard RGB color space to YUV420P. I am struggling to figure out why I keep getting 'Warning: data is not aligned! This can lead to a speedloss' when executing the code. I have looked at a multitude of examples.
int ImageDecoder::rgb2yuv(uint8_t *src,
uint8_t *dest,
uint32_t width,
uint32_t height)
{
struct SwsContext *imgCtx = NULL;
AVFrame *pFrameYUV;
enum AVPixelFormat src_pix_fmt = AV_PIX_FMT_RGB24;
enum AVPixelFormat dst_pix_fmt = AV_PIX_FMT_YUV420P;
int ret;
int size;
const int RGBLinesize[1] = { 3 * (int)width };
pFrameYUV = av_frame_alloc();
pFrameYUV->width = width;
pFrameYUV->height = height;
pFrameYUV->format = dst_pix_fmt;
// Initialize pFrameYUV linesize
ret = av_image_alloc(pFrameYUV->data, pFrameYUV->linesize, pFrameYUV->width, pFrameYUV->height, AV_PIX_FMT_YUV420P, 1);
getLogger()->info("ImageDecoder:{} width={} height={} linesize[0]={} linesize[1]={} linesize[2]={}",
__func__, pFrameYUV->width, pFrameYUV->height, pFrameYUV->linesize[0], pFrameYUV->linesize[1], pFrameYUV->linesize[2]);
size = av_image_get_buffer_size(AV_PIX_FMT_YUV420P, pFrameYUV->width, pFrameYUV->height, 1);
imgCtx = sws_getCachedContext(imgCtx,
width,
height,
AV_PIX_FMT_RGB24,
pFrameYUV->width,
pFrameYUV->height,
AV_PIX_FMT_YUV420P,
SWS_BICUBIC, 0, 0, 0);
if( imgCtx == NULL)
{
getLogger()->error("ERROR: ImageDecoder: {} Cannot initialize the conversion context", __func__);
}
sws_scale(imgCtx,
(const uint8_t* const*)&src,
RGBLinesize,
0,
height,
pFrameYUV->data,
pFrameYUV->linesize);
memcpy(dest, &pFrameYUV->data[0], size);
sws_freeContext(imgCtx);
av_free(pFrameYUV);
}

Answer 1

I hope it helps you.
I am converting YUV444 decoded frames to RGBA format.
AVFrame* RGBFrame = av_frame_alloc();
RGBFrame->width = YUV_frame->width; RGBFrame->format = AV_PIX_FMT_RGBA;
RGBFrame->height = YUV_frame->height;
int ret = av_image_alloc(RGBFrame->data, RGBFrame->linesize, RGBFrame->width, RGBFrame->height, AV_PIX_FMT_RGBA, YUV_frame->pict_type);
if (ret < 0)
return false;
SwsContext* sws_Context = NULL;
sws_Context = sws_getCachedContext(sws_Context, YUV_frame->width, YUV_frame->height, pVideoCodecCtx->pix_fmt,
YUV_frame->width, YUV_frame->height, AV_PIX_FMT_RGBA, SWS_BILINEAR, NULL, NULL, NULL);
if (sws_Context == NULL) return false;
int result = sws_scale(sws_Context, YUV_frame->data, YUV_frame->linesize, 0, (int)YUV_frame->height, RGBFrame->data, RGBFrame->linesize);
if (result < 0) return false;
if (RGBFrame == NULL) {
av_frame_unref(RGBFrame);
return false;
}
sws_freeContext(sws_Context);

Answer 2

int ImageDecoder::rgb2yuv(uint8_t *src,
uint8_t *dest,
uint32_t *outBufferSize,
uint32_t width,
uint32_t height)
{
struct SwsContext *imgCtx = NULL;
uint8_t * RGBData[1] = {src};
const int RGBLinesize[1] = {3 * (int) width};
uint8_t * YUVData[] = {dest,
YUVData[0] + ((int) width * (int) height),
YUVData[1] + (((int) width * (int) height) / 4)};
const int YUVLinesize[] = {(int) width, (int) width / 2, (int) width / 2};
int size;
size = av_image_get_buffer_size(AV_PIX_FMT_YUV420P, width, height, 1);
*outBufferSize = size;
imgCtx = sws_getCachedContext(imgCtx,
width,
height,
AV_PIX_FMT_RGB24,
width,
height,
AV_PIX_FMT_YUV420P,
SWS_BICUBIC, 0, 0, 0);
if (imgCtx == NULL)
{
getLogger()->error("ERROR: ImageDecoder: {} Cannot initialize the conversion context", __func__);
return -1;
}
sws_scale(imgCtx,
RGBData,
RGBLinesize,
0,
height,
YUVData,
YUVLinesize);
sws_freeContext(imgCtx);
return 0;
}