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Linker error by trying example program with ffmpeg
11 mars, par ChrisI think this might be a stupid question and I'm just blind but that thing is driving me nuts for hours now. I downloaded ffmpeg and build it. Now I want to try the thing out in a program but I can't setup cmake to link ffmpeg properly and have no idea what is wrong.
The linker always tells me this:
christoph@christoph-ThinkPad-T490:~/develop/ffmpg_example/build$ make [ 50%] Linking CXX executable test CMakeFiles/test.dir/main.cxx.o: In function `main': main.cxx:(.text+0x180): undefined reference to `av_register_all()' main.cxx:(.text+0x1a7): undefined reference to `avformat_open_input(AVFormatContext**, char const*, AVInputFormat*, AVDictionary**)' main.cxx:(.text+0x1ce): undefined reference to `avformat_find_stream_info(AVFormatContext*, AVDictionary**)' main.cxx:(.text+0x206): undefined reference to `av_dump_format(AVFormatContext*, int, char const*, int)' main.cxx:(.text+0x2bb): undefined reference to `avcodec_find_decoder(AVCodecID)' main.cxx:(.text+0x2fc): undefined reference to `avcodec_alloc_context3(AVCodec const*)' main.cxx:(.text+0x316): undefined reference to `avcodec_copy_context(AVCodecContext*, AVCodecContext const*)' main.cxx:(.text+0x361): undefined reference to `avcodec_open2(AVCodecContext*, AVCodec const*, AVDictionary**)' main.cxx:(.text+0x377): undefined reference to `av_frame_alloc()' main.cxx:(.text+0x383): undefined reference to `av_frame_alloc()' main.cxx:(.text+0x3ba): undefined reference to `avpicture_get_size(AVPixelFormat, int, int)' main.cxx:(.text+0x3d0): undefined reference to `av_malloc(unsigned long)' main.cxx:(.text+0x3ff): undefined reference to `avpicture_fill(AVPicture*, unsigned char const*, AVPixelFormat, int, int)' main.cxx:(.text+0x43d): undefined reference to `sws_getContext(int, int, AVPixelFormat, int, int, AVPixelFormat, int, SwsFilter*, SwsFilter*, double const*)' main.cxx:(.text+0x465): undefined reference to `av_read_frame(AVFormatContext*, AVPacket*)' main.cxx:(.text+0x49f): undefined reference to `avcodec_decode_video2(AVCodecContext*, AVFrame*, int*, AVPacket const*)' main.cxx:(.text+0x4fd): undefined reference to `sws_scale(SwsContext*, unsigned char const* const*, int const*, int, int, unsigned char* const*, int const*)' main.cxx:(.text+0x545): undefined reference to `av_free_packet(AVPacket*)' main.cxx:(.text+0x556): undefined reference to `av_free(void*)' main.cxx:(.text+0x565): undefined reference to `av_frame_free(AVFrame**)' main.cxx:(.text+0x574): undefined reference to `av_frame_free(AVFrame**)' main.cxx:(.text+0x580): undefined reference to `avcodec_close(AVCodecContext*)' main.cxx:(.text+0x58f): undefined reference to `avcodec_close(AVCodecContext*)' main.cxx:(.text+0x59e): undefined reference to `avformat_close_input(AVFormatContext**)' collect2: error: ld returned 1 exit status CMakeFiles/test.dir/build.make:87: recipe for target 'test' failed make[2]: *** [test] Error 1 CMakeFiles/Makefile2:75: recipe for target 'CMakeFiles/test.dir/all' failed make[1]: *** [CMakeFiles/test.dir/all] Error 2 Makefile:83: recipe for target 'all' failed make: *** [all] Error 2The cmake list looks like this:
cmake_minimum_required(VERSION 3.16) project(ffmpeg_test) add_library(avformat STATIC IMPORTED) set_target_properties(avformat PROPERTIES IMPORTED_LOCATION /home/christoph/develop/FFmpeg/build/lib/libavformat.a ) add_library(avcodec STATIC IMPORTED) set_target_properties(avcodec PROPERTIES IMPORTED_LOCATION /home/christoph/develop/FFmpeg/build/lib/libavcodec.a ) add_library(swscale STATIC IMPORTED) set_target_properties(swscale PROPERTIES IMPORTED_LOCATION /home/christoph/develop/FFmpeg/build/lib/libswscale.a ) add_library(avutil STATIC IMPORTED) set_target_properties(avutil PROPERTIES IMPORTED_LOCATION /home/christoph/develop/FFmpeg/build/lib/libavutil.a ) add_executable(test main.cxx) target_link_libraries(test PRIVATE /home/christoph/develop/FFmpeg/build/lib/libavformat.a avcodec swscale avutil ) target_include_directories(test PRIVATE /home/christoph/develop/FFmpeg/build/include)And here are the ffmpeg libs:
christoph@christoph-ThinkPad-T490:~/develop/FFmpeg/build/lib$ ll total 277840 drwxr-xr-x 3 christoph christoph 4096 Dez 7 23:59 ./ drwxr-xr-x 17 christoph christoph 4096 Dez 7 23:59 ../ -rw-r--r-- 1 christoph christoph 173479270 Dez 7 23:59 libavcodec.a -rw-r--r-- 1 christoph christoph 2174910 Dez 7 23:59 libavdevice.a -rw-r--r-- 1 christoph christoph 37992438 Dez 7 23:59 libavfilter.a -rw-r--r-- 1 christoph christoph 59222040 Dez 7 23:59 libavformat.a -rw-r--r-- 1 christoph christoph 4759514 Dez 7 23:59 libavutil.a -rw-r--r-- 1 christoph christoph 695698 Dez 7 23:59 libswresample.a -rw-r--r-- 1 christoph christoph 6164398 Dez 7 23:59 libswscale.a drwxr-xr-x 2 christoph christoph 4096 Dez 7 23:59 pkgconfig/And this is the example code:
#include #includeavcodec.h> #include avformat.h> #include swscale.h> // compatibility with newer API #if LIBAVCODEC_VERSION_INT < AV_VERSION_INT(55,28,1) #define av_frame_alloc avcodec_alloc_frame #define av_frame_free avcodec_free_frame #endif void SaveFrame(AVFrame *pFrame, int width, int height, int iFrame) { FILE *pFile; char szFilename[32]; int y; // Open file sprintf(szFilename, "frame%d.ppm", iFrame); pFile=fopen(szFilename, "wb"); if(pFile==NULL) return; // Write header fprintf(pFile, "P6\n%d %d\n255\n", width, height); // Write pixel data for(y=0; ydata[0]+y*pFrame->linesize[0], 1, width*3, pFile); // Close file fclose(pFile); } int main(int argc, char *argv[]) { // Initalizing these to NULL prevents segfaults! AVFormatContext *pFormatCtx = NULL; int i, videoStream; AVCodecContext *pCodecCtxOrig = NULL; AVCodecContext *pCodecCtx = NULL; AVCodec *pCodec = NULL; AVFrame *pFrame = NULL; AVFrame *pFrameRGB = NULL; AVPacket packet; int frameFinished; int numBytes; uint8_t *buffer = NULL; struct SwsContext *sws_ctx = NULL; if(argc < 2) { printf("Please provide a movie file\n"); return -1; } // Register all formats and codecs av_register_all(); // Open video file if(avformat_open_input(&pFormatCtx, argv[1], NULL, NULL)!=0) return -1; // Couldn't open file // Retrieve stream information if(avformat_find_stream_info(pFormatCtx, NULL)<0) return -1; // Couldn't find stream information // Dump information about file onto standard error av_dump_format(pFormatCtx, 0, argv[1], 0); // Find the first video stream videoStream=-1; for(i=0; inb_streams; i++) if(pFormatCtx->streams[i]->codec->codec_type==AVMEDIA_TYPE_VIDEO) { videoStream=i; break; } if(videoStream==-1) return -1; // Didn't find a video stream // Get a pointer to the codec context for the video stream pCodecCtxOrig=pFormatCtx->streams[videoStream]->codec; // Find the decoder for the video stream pCodec=avcodec_find_decoder(pCodecCtxOrig->codec_id); if(pCodec==NULL) { fprintf(stderr, "Unsupported codec!\n"); return -1; // Codec not found } // Copy context pCodecCtx = avcodec_alloc_context3(pCodec); if(avcodec_copy_context(pCodecCtx, pCodecCtxOrig) != 0) { fprintf(stderr, "Couldn't copy codec context"); return -1; // Error copying codec context } // Open codec if(avcodec_open2(pCodecCtx, pCodec, NULL)<0) return -1; // Could not open codec // Allocate video frame pFrame=av_frame_alloc(); // Allocate an AVFrame structure pFrameRGB=av_frame_alloc(); if(pFrameRGB==NULL) return -1; // Determine required buffer size and allocate buffer numBytes=avpicture_get_size(AV_PIX_FMT_RGB24, pCodecCtx->width, pCodecCtx->height); buffer=(uint8_t *)av_malloc(numBytes*sizeof(uint8_t)); // Assign appropriate parts of buffer to image planes in pFrameRGB // Note that pFrameRGB is an AVFrame, but AVFrame is a superset // of AVPicture avpicture_fill((AVPicture *)pFrameRGB, buffer, AV_PIX_FMT_RGB24, pCodecCtx->width, pCodecCtx->height); // initialize SWS context for software scaling sws_ctx = sws_getContext(pCodecCtx->width, pCodecCtx->height, pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height, AV_PIX_FMT_RGB24, SWS_BILINEAR, NULL, NULL, NULL ); // Read frames and save first five frames to disk i=0; while(av_read_frame(pFormatCtx, &packet)>=0) { // Is this a packet from the video stream? if(packet.stream_index==videoStream) { // Decode video frame avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished, &packet); // Did we get a video frame? if(frameFinished) { // Convert the image from its native format to RGB sws_scale(sws_ctx, (uint8_t const * const *)pFrame->data, pFrame->linesize, 0, pCodecCtx->height, pFrameRGB->data, pFrameRGB->linesize); // Save the frame to disk if(++i<=5) SaveFrame(pFrameRGB, pCodecCtx->width, pCodecCtx->height, i); } } // Free the packet that was allocated by av_read_frame av_free_packet(&packet); } // Free the RGB image av_free(buffer); av_frame_free(&pFrameRGB); // Free the YUV frame av_frame_free(&pFrame); // Close the codecs avcodec_close(pCodecCtx); avcodec_close(pCodecCtxOrig); // Close the video file avformat_close_input(&pFormatCtx); return 0; } -
FFMPEG compile with x264 support for Android
10 mars, par PecanaI am trying to build ffmpeg extensions for media3 (ExoPlayer) for Android
https://github.com/androidx/media/tree/release/libraries/decoder_ffmpeg
Using the default settings everything is fine but if I try to add support to libx264 the build failed. I compiled x264 for Android locally and it worked so the .so file for arm64 is present, I added it to the pkg-config with :
export PKG_CONFIG_PATH=/build/x264/arm64/lib/pkgconfig:$PKG_CONFIG_PATHbut when I try to build ffmpeg with the following command it fails :
./configure \ --prefix=/build/ffmpeg \ --enable-gpl \ --enable-libx264 \ --enable-static \ --enable-pic \ --arch=arm64 \ --target-os=android \ --cross-prefix=$TOOLCHAIN/bin/aarch64-linux-android21- \ --sysroot=$SYSROOTError : ERROR: x264 not found using pkg-config
But it is not due to pkg-config as the command:
pkg-config --cflags --libs x264reports : -DX264_API_IMPORTS -I/build/x264/arm64/include -L/build/x264/arm64/lib -lx264
Any idea on how to fix it ?
Thank you :-)
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How to seek one frame forward in ffmpeg [closed]
10 mars, par Summiti want to seek one frame forward when i call this function but it gets stuck on the first frame seeked and does not move forward.
void seekFrameUp() { if (!fmt_ctx || video_stream_index == -1) return; AVRational frame_rate = fmt_ctx->streams[video_stream_index]->r_frame_rate; if (frame_rate.num == 0) return; // Avoid division by zero // Compute frame duration in AV_TIME_BASE_Q int64_t frame_duration = av_rescale_q(1, av_make_q(frame_rate.den, frame_rate.num), AV_TIME_BASE_Q); int64_t next_pts = requestedTimestamp + frame_duration; qDebug() << "Seeking forward: " << next_pts << " (Current PTS: " << requestedTimestamp << ", Frame Duration: " << frame_duration << ")"; requestFrameAt(next_pts); // Update the requested timestamp after seeking requestedTimestamp = next_pts; } void requestFrameAt(int64_t timestamp) { { std::lock_guard lock(mtx); decoding = true; // Ensure the thread keeps decoding when needed } cv.notify_one(); } void decodeLoop() { while (!stopThread) { std::unique_lock lock(mtx); cv.wait(lock, [this] { return decoding || stopThread; }); if (stopThread) break; // Avoid redundant seeking if (requestedTimestamp == lastRequestedTimestamp) { decoding = false; continue; } lastRequestedTimestamp.store(requestedTimestamp.load()); int64_t target_pts = av_rescale_q(requestedTimestamp, AV_TIME_BASE_Q, fmt_ctx->streams[video_stream_index]->time_base); target_pts = FFMAX(target_pts, 0); // Ensure it's not negative if (av_seek_frame(fmt_ctx, video_stream_index, target_pts, AVSEEK_FLAG_ANY) >= 0) { avcodec_flush_buffers(codec_ctx); // Clear old frames from the decoder qDebug() << "Seek successful to PTS:" << target_pts; } else { qDebug() << "Seeking failed!"; decoding = false; continue; } lock.unlock(); // Keep decoding until we receive a valid frame bool frameDecoded = false; while (av_read_frame(fmt_ctx, pkt) >= 0) { if (pkt->stream_index == video_stream_index) { if (avcodec_send_packet(codec_ctx, pkt) == 0) { while (avcodec_receive_frame(codec_ctx, frame) == 0) { qDebug() << "FRAME DECODED ++++++++++++ PTS:" << frame->pts; if (frame->pts != AV_NOPTS_VALUE) { // Rescale PTS to AV_TIME_BASE_Q int64_t pts_in_correct_base = av_rescale_q(frame->pts, fmt_ctx->streams[video_stream_index]->time_base, AV_TIME_BASE_Q); // Ensure we don’t reset to 0 incorrectly if (pts_in_correct_base > 0) { current_pts.store(pts_in_correct_base); qDebug() << "Updated current_pts to:" << current_pts.load(); } else { qDebug() << "Warning: Decoded frame has PTS <= 0, keeping last valid PTS."; } } else { qDebug() << "Invalid frame->pts (AV_NOPTS_VALUE)"; } QImage img = convertFrameToImage(frame); emit frameDecodedSignal(img); frameDecoded = true; break; // Exit after the first valid frame } if (frameDecoded) { decoding = (requestedTimestamp != lastRequestedTimestamp); break; } } } av_packet_unref(pkt); } } } -
How to Use SVG Image Files Directly in FFmpeg ? [closed]
10 mars, par Pubg MobileI generated a bar chart race using the Flourish Studio website and captured the frames as a PDF sequence using a Python Playwright script. Then, I converted all the PDF files into SVG format using the following Python script, because SVG is the only image format that maintains quality without loss when zoomed in:
import os import subprocess import multiprocessing # Define paths pdf2svg_path = r"E:\Desktop\dist-64bits\pdf2svg.exe" # Full path to pdf2svg.exe input_dir = r"E:\Desktop\New folder (4)\New folder" output_dir = r"E:\Desktop\New folder (4)\New folder (2)" # Ensure output directory exists os.makedirs(output_dir, exist_ok=True) def convert_pdf_to_svg(pdf_file): """ Convert a single PDF file to SVG. """ input_pdf = os.path.join(input_dir, pdf_file) output_svg = os.path.join(output_dir, os.path.splitext(pdf_file)[0] + ".svg") try: subprocess.run([pdf2svg_path, input_pdf, output_svg], check=True) print(f"Converted: {pdf_file} -> {output_svg}") except FileNotFoundError: print(f"Error: Could not find {pdf2svg_path}. Make sure the path is correct.") except subprocess.CalledProcessError: print(f"Error: Conversion failed for {pdf_file}") if __name__ == "__main__": # Get list of PDF files in input directory pdf_files = [f for f in os.listdir(input_dir) if f.lower().endswith(".pdf")] # Use multiprocessing to speed up conversion with multiprocessing.Pool(processes=multiprocessing.cpu_count()) as pool: pool.map(convert_pdf_to_svg, pdf_files) print("All conversions completed!")Problem:
Now, I want to use these SVG images in FFmpeg to create a high-quality video file. However, FFmpeg does not support SVG files directly, and I have read that I must convert SVG files into PNG before using them in FFmpeg. The problem is that PNG images reduce quality, especially when zooming in, which is why I want to avoid converting to PNG.
Is there any way to use SVG files directly in FFmpeg or another method to convert them into a high-quality video while maintaining full resolution? Any ideas or suggestions would be greatly appreciated!
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OpenGL to FFMpeg encode [closed]
10 mars, par Ian A McElhennyI have a
openglbuffer that I need to forward directly toffmpegto do the nvenc basedh264encoding.My current way of doing this is
glReadPixelsto get the pixels out of the frame buffer and then passing that pointer intoffmpegsuch that it can encode the frame intoH264packets forRTSP. However, this is bad because I have to copy bytes out of the GPU ram into CPU ram, to only copy them back into the GPU for encoding.How do you do bypass the need to copy to and from the CPU?
