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  • ffmpeg : sws_scale returning wrong values in plane V during RGB to YUV420 conversion

    1er mars 2012, par Sambatyon

    I am trying to use sws_scale to transform an image from RGB to YUV420P. The code I use in C++ is the following:

    SwsContext *swscontext = sws_getContext(current_width,
                                        current_height,
                                        PIX_FMT_RGB24,
                                        current_width,
                                        current_height,
                                        PIX_FMT_YUV420P,
                                        SWS_FAST_BILINEAR,
                                        NULL,
                                        NULL,
                                        NULL);
const int srcstride[3] = {current_width * 3, 0, 0};
BYTE *data_pos[3] = {data, NULL, NULL};
BYTE *dest[3] = {yuv,
                yuv + current_width * current_height,
                yuv + (current_width * current_height) 
                    + ((current_width * current_height) / 2)};
const int dststride[3] = {current_width, current_width / 2, current_width / 2};
sws_scale(swscontext, data_pos, srcstride, 0, current_height,
          dest, dststride);

    The Y and U planes are encoded properly but the V plane is completely written with the value 0x80 I wonder if I am doing anything wrong.

  • prores to H264 encoding

    1er mars 2012, par user1239878

    I am trying to encode a ProRes 422 an a DVCProHD mov video files to a H264 .mov output, using FFMPEG command line. It seems that using default setting:

    ffmpeg -i filename.mov vcodec libx264 -acodec copy -s 1280x1080 -b:v 15000k -y output.mov

    the quality of the output video is very low.

    Is there any presetting you've used to encode ProRes videos to H264 that would provide the best video experience on output?

  • Convert MMS streaming to any Android format

    1er mars 2012, par Giuseppe

    I have the following stream mms://77.238.11.5:8080, you can access it using Windows Mediaplayer.

    I don't find any solution to view it on Android devices using MediaPlayer or VideoView, so my idea is to convert is using VLC or FFMPEG to a different format like MP4 or else.

  • error : expected '=', ',', ' ;', 'asm' or '__attribute__' before 'secret' after Android ndk-build

    29 février 2012, par David Ohanyan

    I have compiled ffmpeg for android ndk r7b in Ubuntu 11.10 and now I am trying to use it. I added to my jni directory include folder, which contains header files, and lib
    directory which contains .so files of ffmpeg.
    After ndk-build command I get expected '=', ',', ';', 'asm' or 'attribute' before 'secret' error. I read a lot of posts connected with this error and most of them insist that C compiler causes this error and they advice to use g++. I removed gcc compiler and installed g++, but the error doesn't disappear.

  • sws_scale returning wrong values in plane V in RGB to YUV420 conversion

    29 février 2012, par Sambatyon

    I am trying to use sws_scale to transform an image from RGB to YUV420P. The code I use in C++ is the following:

    SwsContext *swscontext = sws_getContext(current_width,
                                        current_height,
                                        PIX_FMT_RGB24,
                                        current_width,
                                        current_height,
                                        PIX_FMT_YUV420P,
                                        SWS_FAST_BILINEAR,
                                        NULL,
                                        NULL,
                                        NULL);
const int srcstride[3] = {current_width * 3, 0, 0};
BYTE *data_pos[3] = {data, NULL, NULL};
BYTE *dest[3] = {yuv,
                yuv + current_width * current_height,
                yuv + (current_width * current_height) 
                    + ((current_width * current_height) / 2)};
const int dststride[3] = {current_width, current_width / 2, current_width / 2};
sws_scale(swscontext, data_pos, srcstride, 0, current_height,
          dest, dststride);

    The Y and U planes are encoded properly but the V plane is completely written with the value 0x80 I wonder if I am doing anything wrong.

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