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SPIP - plugins - embed code - Exemple
2 septembre 2013, par
Mis à jour : Septembre 2013
Langue : français
Type : Image
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Sur d’autres sites (11069)
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How can I combine HDR video with a still PNG in FFMPEG without messing up colors ?
2 juin 2022, par RobertI'm trying to add a still image to the end of a video as a title-card. Normally this is simple, but the video is HDR (shot on an iPhone) and for reasons I don't understand that's causing the colors in the PNG to go nuts.


Here's the original png :



Here's a screenshot from the end of the output video :



Clearly something is amiss. I made the PNG image in Photoshop from a photo, and I've tried it with and without embedding the color profile without any noticeable difference.


Here's the command for ffmpeg :


ffmpeg -y\
 -t 5 -i '../inputs/video.MOV'\
 -loop 1 -t 5 -i '../../common/end-youtube.png'\
 -filter_complex '
[1:v] fade=type=in:duration=1:alpha=1, setpts=PTS-STARTPTS+5/TB[end];
[0:v][end] overlay [outV]
'\
 -map [outV] '../test.mp4'


I've tried this with non-HDR videos and the colors look perfectly normal, so clearly the HDRness is somehow involved. I've also tried adding this line to set the colorspace etc of the output. It helps with the PNG (although it's not perfect) but then the video is washed out.


-colorspace bt709 -color_trc bt709 -color_primaries bt709 -color_range mpeg \


I don't really care if the output video is HDR or not, as long as the video and png parts both look visually close to the inputs. This is something I'll need to do to many videos, so if possible a solution that doesn't involve tweaking colors for each one would be ideal.


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Render YUV video in OpenGL of ffmpeg using CVPixelBufferRef and Shaders
4 septembre 2012, par resident_I'm using to render YUV frames of ffmpeg with the iOS 5.0 method "CVOpenGLESTextureCacheCreateTextureFromImage".
I'm using like the apple example GLCameraRipple
My result in iPhone screen is this : iPhone Screen
I need to know I'm doing wrong.
I put part of my code to find errors.
ffmpeg configure frames :
ctx->p_sws_ctx = sws_getContext(ctx->p_video_ctx->width,
ctx->p_video_ctx->height,
ctx->p_video_ctx->pix_fmt,
ctx->p_video_ctx->width,
ctx->p_video_ctx->height,
PIX_FMT_YUV420P, SWS_FAST_BILINEAR, NULL, NULL, NULL);
// Framebuffer for RGB data
ctx->p_frame_buffer = malloc(avpicture_get_size(PIX_FMT_YUV420P,
ctx->p_video_ctx->width,
ctx->p_video_ctx->height));
avpicture_fill((AVPicture*)ctx->p_picture_rgb, ctx->p_frame_buffer,PIX_FMT_YUV420P,
ctx->p_video_ctx->width,
ctx->p_video_ctx->height);My render method :
if (NULL == videoTextureCache) {
NSLog(@"displayPixelBuffer error");
return;
}
CVPixelBufferRef pixelBuffer;
CVPixelBufferCreateWithBytes(kCFAllocatorDefault, mTexW, mTexH, kCVPixelFormatType_420YpCbCr8BiPlanarVideoRange, buffer, mFrameW * 3, NULL, 0, NULL, &pixelBuffer);
CVReturn err;
// Y-plane
glActiveTexture(GL_TEXTURE0);
err = CVOpenGLESTextureCacheCreateTextureFromImage(kCFAllocatorDefault,
videoTextureCache,
pixelBuffer,
NULL,
GL_TEXTURE_2D,
GL_RED_EXT,
mTexW,
mTexH,
GL_RED_EXT,
GL_UNSIGNED_BYTE,
0,
&_lumaTexture);
if (err)
{
NSLog(@"Error at CVOpenGLESTextureCacheCreateTextureFromImage %d", err);
}
glBindTexture(CVOpenGLESTextureGetTarget(_lumaTexture), CVOpenGLESTextureGetName(_lumaTexture));
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
// UV-plane
glActiveTexture(GL_TEXTURE1);
err = CVOpenGLESTextureCacheCreateTextureFromImage(kCFAllocatorDefault,
videoTextureCache,
pixelBuffer,
NULL,
GL_TEXTURE_2D,
GL_RG_EXT,
mTexW/2,
mTexH/2,
GL_RG_EXT,
GL_UNSIGNED_BYTE,
1,
&_chromaTexture);
if (err)
{
NSLog(@"Error at CVOpenGLESTextureCacheCreateTextureFromImage %d", err);
}
glBindTexture(CVOpenGLESTextureGetTarget(_chromaTexture), CVOpenGLESTextureGetName(_chromaTexture));
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glBindFramebuffer(GL_FRAMEBUFFER, defaultFramebuffer);
// Set the view port to the entire view
glViewport(0, 0, backingWidth, backingHeight);
static const GLfloat squareVertices[] = {
1.0f, 1.0f,
-1.0f, 1.0f,
1.0f, -1.0f,
-1.0f, -1.0f,
};
GLfloat textureVertices[] = {
1, 1,
1, 0,
0, 1,
0, 0,
};
// Draw the texture on the screen with OpenGL ES 2
[self renderWithSquareVertices:squareVertices textureVertices:textureVertices];
// Flush the CVOpenGLESTexture cache and release the texture
CVOpenGLESTextureCacheFlush(videoTextureCache, 0);
CVPixelBufferRelease(pixelBuffer);
[moviePlayerDelegate bufferDone];RenderWithSquareVertices method
- (void)renderWithSquareVertices:(const GLfloat*)squareVertices textureVertices:(const GLfloat*)textureVertices
{
// Use shader program.
glUseProgram(shader.program);
// Update attribute values.
glVertexAttribPointer(ATTRIB_VERTEX, 2, GL_FLOAT, 0, 0, squareVertices);
glEnableVertexAttribArray(ATTRIB_VERTEX);
glVertexAttribPointer(ATTRIB_TEXTUREPOSITON, 2, GL_FLOAT, 0, 0, textureVertices);
glEnableVertexAttribArray(ATTRIB_TEXTUREPOSITON);
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
// Present
glBindRenderbuffer(GL_RENDERBUFFER, colorRenderbuffer);
[context presentRenderbuffer:GL_RENDERBUFFER];}
My fragment shader :
uniform sampler2D SamplerY;
uniform sampler2D SamplerUV;
varying highp vec2 _texcoord;
void main()
{
mediump vec3 yuv;
lowp vec3 rgb;
yuv.x = texture2D(SamplerY, _texcoord).r;
yuv.yz = texture2D(SamplerUV, _texcoord).rg - vec2(0.5, 0.5);
// BT.601, which is the standard for SDTV is provided as a reference
/* rgb = mat3( 1, 1, 1,
0, -.34413, 1.772,
1.402, -.71414, 0) * yuv;*/
// Using BT.709 which is the standard for HDTV
rgb = mat3( 1, 1, 1,
0, -.18732, 1.8556,
1.57481, -.46813, 0) * yuv;
gl_FragColor = vec4(rgb, 1);
}Very thanks,
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Why mp4 can not shared on Facebook or Instagram on Android ?
8 janvier 2023, par JánosThis is the file : https://t44-post-cover.s3.eu-central-1.amazonaws.com/2e3s.mp4


When I download and try share, it fails. Why ? This is the parameters was rendered. Downloading and sharing works from iPhone to Facebook on Messenger or Instagram, but not from Android phone to Facebook on Messenger or Instagram.


What parameters
ffpmpegneed to be able to sharemp4from Android to Facebook / Instagram ?

await new Promise<void>((resolve, reject) => {
 ffmpeg()
 .setFfmpegPath(pathToFfmpeg)
 .input(`/tmp/input_${imgId}.gif`)
 .inputFormat('gif')
 .inputFPS(30)
 .input('anullsrc')
 .inputFormat('lavfi')
 .audioCodec('aac')
 .audioChannels(2)
 .audioFilters(['apad'])
 .videoCodec('libx264')
 .videoBitrate(1000)
 .videoFilters([
 'tpad=stop_mode=clone:stop_duration=2',
 'scale=trunc(iw/2)*2:trunc(ih/2)*2:flags=lanczos,split[s0][s1];[s0]palettegen[p];[s1][p]paletteuse',
 ])
 .fps(30)
 .duration(5)
 .format('mp4')
 .outputOptions([
 '-pix_fmt yuvj420p',
 '-profile:v baseline',
 '-level 3.0',
 '-crf 17',
 '-movflags +faststart',
 '-movflags frag_keyframe+empty_moov',
 ])
 .output(`/tmp/output_${imgId}.mp4`)
 .on('end', () => {
 console.log('MP4 video generated')
 resolve()
 })
 .on('error', (e) => {
 console.log(e)
 reject()
 })
 .run()
 })
</void>

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