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Ffmpeg fail on avformat_open_input() while try to encode YUV420p uncompressed video, input from custom IO instead of file. (C++ code)
25 avril 2023, par devprogI am trying to encode YUV420p raw data that being streamed live from a private memory implementation. It didn't work. As a preliminary stage to private memory reading, and after some searches, I tried to read Custom IO input according ffmpeg example. This didn't work either. So, for my tests I created YUV file using


ffmpeg -f lavfi -i testsrc=duration=10:size=1920x1080:rate=30 1920x1080p30_10s.mp4


create a mp4 file. As a note, it turns out that it creates mp4 file with yuv444 color system. I changed it to yuv420p with


ffmpeg -i 1920x1080p30_10s.mp4 -c:v libx264 -pix_fmt yuv420p 1920x1080p30_10s_420p.mp4


then create a yuv file with


ffmpeg -i 1920x1080p30_10s_420p.mp4 -c:v rawvideo -pixel_format yuv420p output_1920x1080_420p.yuv


Test the output_1920x1080_420p.yuv with ffplay, looks good. This file will be my input to custom IO operation.


Then wrote a sample code as follows (based on several links) :
avio_reading ffmpeg example.
Creating Custom FFmpeg IO-Context


Code fail with the function


if ((ret = avformat_open_input(&pAVFormatContext, "IO", NULL, &options_in) < 0) )
 {
 printf ("err=%d\n", ret);
 av_strerror(ret, errbuf, sizeof(errbuf));
 fprintf(stderr, "Unable to open err=%s\n", errbuf);
 return false;
 }


Some notes :


- 

- I added the code, the compile command & the output
- I tried use with option parameters to avformat_open_input() & without, it failed.
- I tried to use with seek callback to avio_alloc_context() & without, it failed.
- I tries to use instead of YUV some mp4 file and looks as running (didn't fail) - BUT it is NOT what I need. I Need a YUV input










Can anyone help ? Is it even possible ?


My following code compiles with :


g++ ffmpeg_custom_io.cpp -lavformat -lavdevice -lavcodec -lavutil -lswscale -lswresample -lpthread -pthread -o ffmpeg_custom_io


and whole code is as follows :


using namespace std;

#include 
#include 
#include 
#include <iostream>

extern "C" {
 #include <libavformat></libavformat>avformat.h>
 #include <libavcodec></libavcodec>avcodec.h>
 
 #include <libavutil></libavutil>opt.h>
 #include <libavutil></libavutil>imgutils.h>
 #include <libavutil></libavutil>file.h>
}


struct buffer_data {
 uint8_t * bd_ptr;
 size_t bd_size; ///< size left in the buffer
};

int readFileBuffer(void *opaque, uint8_t *buf, int buf_size)
{

 printf("Start reading custom IO\n");
 struct buffer_data *bd = (struct buffer_data *)opaque;
 buf_size = FFMIN(buf_size, bd->bd_size);

 printf("min buf size:%d\n", buf_size);

 if (!buf_size) {
 printf("return -1, size = %d\n", buf_size);
 return -1;
 }
 printf("ptr:%p size:%zu\n", bd->bd_ptr, bd->bd_size);

 /* copy internal buffer data to buf */
 memcpy(buf, bd->bd_ptr, buf_size);
 bd->bd_ptr += buf_size;
 bd->bd_size -= buf_size;
 printf("End reading custom IO\n");
 return buf_size;

}

int64_t seekFunction(void* opaque, int64_t offset, int whence)
{
 std::cout << "SEEK " << std::endl;
 if (whence == AVSEEK_SIZE)
 return -1; // I don't know "size of my handle in bytes"
}

static void encode(AVCodecContext *enc_ctx, AVFrame *frame, AVPacket *pkt,
 FILE *outfile)
{
 int ret;

 /* send the frame to the encoder */
 if (frame)
 printf("Send frame %3" PRId64 "\n", frame->pts);

 ret = avcodec_send_frame(enc_ctx, frame);
 if (ret < 0) {
 fprintf(stderr, "Error sending a frame for encoding\n");
 exit(1);
 }

 while (ret >= 0) {
 ret = avcodec_receive_packet(enc_ctx, pkt);
 if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
 return;
 else if (ret < 0) {
 fprintf(stderr, "Error during encoding\n");
 exit(1);
 }

 printf("Write packet %3" PRId64 " (size=%5d)\n", pkt->pts, pkt->size);
 fwrite(pkt->data, 1, pkt->size, outfile);
 av_packet_unref(pkt);
 }
}

int main(int argc, char **argv)
{

 av_log_set_level(AV_LOG_MAX_OFFSET);

 AVFormatContext* pAVFormatContext;
 uint8_t *buffer = NULL, *avio_ctx_buffer = NULL;
 size_t buffer_size, avio_ctx_buffer_size = 32768;

 int ret = 0;
 char errbuf[100];

 // Alloc format context
 //--------------------
 if ( !(pAVFormatContext = avformat_alloc_context()) )
 {
 ret = AVERROR(ENOMEM);
 std::cout << "error=" << ret << " Fail to allocate avformat_alloc_context()\n";
 return false;
 }

 // Copy from ffmpeg example - bd buffer
 //--------------------
 struct buffer_data bd = { 0, 0 };

 // slurp file content into buffer
 ret = av_file_map("output_1920x1080_420p.yuv", &buffer, &buffer_size, 0, NULL);
 if (ret < 0)
 {
 std::cout << "error=" << ret << " Fail to allocate avformat_alloc_context()\n";
 return false;
 }

 // fill opaque structure used by the AVIOContext read callback
 bd.bd_ptr = buffer;
 bd.bd_size = buffer_size;

 // Prepare AVIO context
 //--------------------
 avio_ctx_buffer = static_cast(av_malloc(avio_ctx_buffer_size + AV_INPUT_BUFFER_PADDING_SIZE));

 if (!avio_ctx_buffer) {
 ret = AVERROR(ENOMEM);
 std::cout << "error=" << ret << " Fail to allocate av_malloc()\n";
 return false;
 }

 AVIOContext* pAVIOContext = avio_alloc_context(avio_ctx_buffer,
 avio_ctx_buffer_size,
 0,
 &bd,
 readFileBuffer,
 NULL,
 seekFunction);

 if (!pAVIOContext) {
 ret = AVERROR(ENOMEM);
 std::cout << "error=" << ret << " Fail to allocate avio_alloc_context()\n";
 return false;
 }

 pAVFormatContext->pb = pAVIOContext;
 pAVFormatContext->flags = AVFMT_FLAG_CUSTOM_IO; // - NOT SURE ABOUT THIS FLAG

 // Handle ffmpeg input
 //--------------------
 AVDictionary* options_in = NULL;
 //av_dict_set(&options_in, "framerate", "30", 0);
 av_dict_set(&options_in, "video_size", "1920x1080", 0);
 av_dict_set(&options_in, "pixel_format", "yuv420p", 0);
 av_dict_set(&options_in, "vcodec", "rawvideo", 0);

 if ((ret = avformat_open_input(&pAVFormatContext, "IO", NULL, &options_in) < 0) )
 {
 printf ("err=%d\n", ret);
 av_strerror(ret, errbuf, sizeof(errbuf));
 fprintf(stderr, "Unable to open err=%s\n", errbuf);
 return false;
 }

 //Raw video doesn't contain any stream information.
 //if ((ret = avformat_find_stream_info(pAVFormatContext, 0)) < 0) {
 // fprintf(stderr, "Failed to retrieve input stream information");
 //}

 AVCodec* pAVCodec = avcodec_find_decoder(AV_CODEC_ID_RAWVIDEO); //Get pointer to rawvideo codec.

 AVCodecContext* pAVCodecContext = avcodec_alloc_context3(pAVCodec); //Allocate codec context.

 //Fill the codec context based on the values from the codec parameters.
 AVStream *vid_stream = pAVFormatContext->streams[0];
 avcodec_parameters_to_context(pAVCodecContext, vid_stream->codecpar);

 avcodec_open2(pAVCodecContext, pAVCodec, NULL); //Open the codec

 //Allocate memory for packet and frame
 AVPacket* pAVPacketIn = av_packet_alloc();
 AVFrame* pAVFrameOut = av_frame_alloc();

 /* find the mpeg1video encoder */
 AVCodec* pAVCodecOut = avcodec_find_encoder_by_name("libx264");
 if (!pAVCodecOut) {
 fprintf(stderr, "Codec '%s' not found\n", "libx264");
 exit(1);
 }

 AVCodecContext* pAVCodecContextOut = avcodec_alloc_context3(pAVCodecOut);
 if (!pAVCodecContextOut) {
 fprintf(stderr, "Could not allocate video codec context\n");
 exit(1);
 }

 AVPacket* pAVPacketOut = av_packet_alloc();
 if (!pAVPacketOut)
 exit(1);

 /* put sample parameters */
 pAVCodecContextOut->bit_rate = 2000000;
 /* resolution must be a multiple of two */
 pAVCodecContextOut->width = 1280;
 pAVCodecContextOut->height = 720;
 /* frames per second */
 pAVCodecContextOut->time_base = (AVRational){1, 30};
 pAVCodecContextOut->framerate = (AVRational){30, 1};

 /* emit one intra frame every ten frames
 * check frame pict_type before passing frame
 * to encoder, if frame->pict_type is AV_PICTURE_TYPE_I
 * then gop_size is ignored and the output of encoder
 * will always be I frame irrespective to gop_size
 */
 pAVCodecContextOut->gop_size = 10;
 pAVCodecContextOut->max_b_frames = 0;
 pAVCodecContextOut->pix_fmt = AV_PIX_FMT_YUV420P;

 if (pAVCodecOut->id == AV_CODEC_ID_H264)
 av_opt_set(pAVCodecContextOut->priv_data, "preset", "slow", 0);

 /* open it */
 ret = avcodec_open2(pAVCodecContextOut, pAVCodecOut, NULL);
 if (ret < 0) {
 //fprintf(stderr, "Could not open codec: %s\n", av_err2str(ret));
 exit(1);
 }

 FILE* filename_out = fopen("out_vid_h264.mp4", "wb");
 if (!filename_out) {
 fprintf(stderr, "Could not open %s\n", "out_vid_h264.mp4");
 exit(1);
 }

 pAVFrameOut->format = pAVCodecContextOut->pix_fmt;
 pAVFrameOut->width = pAVCodecContextOut->width;
 pAVFrameOut->height = pAVCodecContextOut->height;


 uint8_t endcode_suf[] = { 0, 0, 1, 0xb7 };
 int i = 0;
 //Read video frames and pass through the decoder.
 //Note: Since the video is rawvideo, we don't really have to pass it through the decoder.
 while (av_read_frame(pAVFormatContext, pAVPacketIn) >= 0)
 {
 //The video is not encoded - passing through the decoder is simply copy the data.
 avcodec_send_packet(pAVCodecContext, pAVPacketIn); //Supply raw packet data as input to the "decoder".
 avcodec_receive_frame(pAVCodecContext, pAVFrameOut); //Return decoded output data from the "decoder".

 fflush(stdout);

 pAVFrameOut->pts = i++;

 /* encode the image */
 encode(pAVCodecContextOut, pAVFrameOut, pAVPacketOut, filename_out);
 }

 /* flush the encoder */
 encode(pAVCodecContextOut, NULL, pAVPacketOut, filename_out);

 /* Add sequence end code to have a real MPEG file.
 It makes only sense because this tiny examples writes packets
 directly. This is called "elementary stream" and only works for some
 codecs. To create a valid file, you usually need to write packets
 into a proper file format or protocol; see mux.c.
 */
 if (pAVCodecOut->id == AV_CODEC_ID_MPEG1VIDEO || pAVCodecOut->id == AV_CODEC_ID_MPEG2VIDEO)
 fwrite(endcode_suf, 1, sizeof(endcode_suf), filename_out);
 fclose(filename_out);


 return 0;
}
</iostream>

The output


./ffmpeg_custom_io 
Start reading custom IO
min buf size:32768
ptr:0x7f236a200000 size:933120000
End reading custom IO
Probing adp score:25 size:2048
Probing adp score:25 size:4096
Probing adp score:25 size:8192
Probing adp score:25 size:16384
Start reading custom IO
min buf size:32768
ptr:0x7f236a208000 size:933087232
End reading custom IO
Start reading custom IO
min buf size:65536
ptr:0x7f236a210000 size:933054464
End reading custom IO
Start reading custom IO
min buf size:131072
ptr:0x7f236a220000 size:932988928
End reading custom IO
Start reading custom IO
min buf size:262144
ptr:0x7f236a240000 size:932857856
End reading custom IO
Start reading custom IO
min buf size:524288
ptr:0x7f236a280000 size:932595712
End reading custom IO
err=1
Unable to open err=Error number 1 occurred



I tried all as noted above expecting avformat_open_input() will succeed, but it failed.


-
Encoding YUV420p uncompressed video that comes from custom IO instead of file. (C++ code)
24 avril 2023, par devprogI am trying to encode YUV420p raw data that being streamed live from a private memory implementation. It didn't work. As a preliminary stage to private memory reading, and after some searches, I tried to read Custom IO input according ffmpeg example. This didn't work either. So, for my tests I created YUV file using


ffmpeg -f lavfi -i testsrc=duration=10:size=1920x1080:rate=30 1920x1080p30_10s.mp4


create a mp4 file. As a note, it turns out that it creates mp4 file with yuv444 color system. I changed it to yuv420p with


ffmpeg -i 1920x1080p30_10s.mp4 -c:v libx264 -pix_fmt yuv420p 1920x1080p30_10s_420p.mp4


then create a yuv file with


ffmpeg -i 1920x1080p30_10s_420p.mp4 -c:v rawvideo -pixel_format yuv420p output_1920x1080_420p.yuv


Test the output_1920x1080_420p.yuv with ffplay, looks good. This file will be my input to custom IO operation.


Then wrote a sample code as follows (based on several links) :
avio_reading ffmpeg example.
Creating Custom FFmpeg IO-Context


Code fail with the function


if ((ret = avformat_open_input(&pAVFormatContext, "IO", NULL, &options_in) < 0) )
 {
 printf ("err=%d\n", ret);
 av_strerror(ret, errbuf, sizeof(errbuf));
 fprintf(stderr, "Unable to open err=%s\n", errbuf);
 return false;
 }


Some notes :


- 

- I added the code, the compile command & the output
- I tried use with option parameters to avformat_open_input() & without, it failed.
- I tried to use with seek callback to avio_alloc_context() & without, it failed.
- I tries to use instead of YUV some mp4 file and looks as running (didn't fail) - BUT it is NOT what I need. I Need a YUV input










Can anyone help ? Is it even possible ?


My following code compiles with :


g++ ffmpeg_custom_io.cpp -lavformat -lavdevice -lavcodec -lavutil -lswscale -lswresample -lpthread -pthread -o ffmpeg_custom_io


and whole code is as follows :


using namespace std;

#include 
#include 
#include 
#include <iostream>

extern "C" {
 #include <libavformat></libavformat>avformat.h>
 #include <libavcodec></libavcodec>avcodec.h>
 
 #include <libavutil></libavutil>opt.h>
 #include <libavutil></libavutil>imgutils.h>
 #include <libavutil></libavutil>file.h>
}


struct buffer_data {
 uint8_t * bd_ptr;
 size_t bd_size; ///< size left in the buffer
};

int readFileBuffer(void *opaque, uint8_t *buf, int buf_size)
{

 printf("Start reading custom IO\n");
 struct buffer_data *bd = (struct buffer_data *)opaque;
 buf_size = FFMIN(buf_size, bd->bd_size);

 printf("min buf size:%d\n", buf_size);

 if (!buf_size) {
 printf("return -1, size = %d\n", buf_size);
 return -1;
 }
 printf("ptr:%p size:%zu\n", bd->bd_ptr, bd->bd_size);

 /* copy internal buffer data to buf */
 memcpy(buf, bd->bd_ptr, buf_size);
 bd->bd_ptr += buf_size;
 bd->bd_size -= buf_size;
 printf("End reading custom IO\n");
 return buf_size;

}

int64_t seekFunction(void* opaque, int64_t offset, int whence)
{
 std::cout << "SEEK " << std::endl;
 if (whence == AVSEEK_SIZE)
 return -1; // I don't know "size of my handle in bytes"
}

static void encode(AVCodecContext *enc_ctx, AVFrame *frame, AVPacket *pkt,
 FILE *outfile)
{
 int ret;

 /* send the frame to the encoder */
 if (frame)
 printf("Send frame %3" PRId64 "\n", frame->pts);

 ret = avcodec_send_frame(enc_ctx, frame);
 if (ret < 0) {
 fprintf(stderr, "Error sending a frame for encoding\n");
 exit(1);
 }

 while (ret >= 0) {
 ret = avcodec_receive_packet(enc_ctx, pkt);
 if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
 return;
 else if (ret < 0) {
 fprintf(stderr, "Error during encoding\n");
 exit(1);
 }

 printf("Write packet %3" PRId64 " (size=%5d)\n", pkt->pts, pkt->size);
 fwrite(pkt->data, 1, pkt->size, outfile);
 av_packet_unref(pkt);
 }
}

int main(int argc, char **argv)
{

 av_log_set_level(AV_LOG_MAX_OFFSET);

 AVFormatContext* pAVFormatContext;
 uint8_t *buffer = NULL, *avio_ctx_buffer = NULL;
 size_t buffer_size, avio_ctx_buffer_size = 32768;

 int ret = 0;
 char errbuf[100];

 // Alloc format context
 //--------------------
 if ( !(pAVFormatContext = avformat_alloc_context()) )
 {
 ret = AVERROR(ENOMEM);
 std::cout << "error=" << ret << " Fail to allocate avformat_alloc_context()\n";
 return false;
 }

 // Copy from ffmpeg example - bd buffer
 //--------------------
 struct buffer_data bd = { 0, 0 };

 // slurp file content into buffer
 ret = av_file_map("output_1920x1080_420p.yuv", &buffer, &buffer_size, 0, NULL);
 if (ret < 0)
 {
 std::cout << "error=" << ret << " Fail to allocate avformat_alloc_context()\n";
 return false;
 }

 // fill opaque structure used by the AVIOContext read callback
 bd.bd_ptr = buffer;
 bd.bd_size = buffer_size;

 // Prepare AVIO context
 //--------------------
 avio_ctx_buffer = static_cast(av_malloc(avio_ctx_buffer_size + AV_INPUT_BUFFER_PADDING_SIZE));

 if (!avio_ctx_buffer) {
 ret = AVERROR(ENOMEM);
 std::cout << "error=" << ret << " Fail to allocate av_malloc()\n";
 return false;
 }

 AVIOContext* pAVIOContext = avio_alloc_context(avio_ctx_buffer,
 avio_ctx_buffer_size,
 0,
 &bd,
 readFileBuffer,
 NULL,
 seekFunction);

 if (!pAVIOContext) {
 ret = AVERROR(ENOMEM);
 std::cout << "error=" << ret << " Fail to allocate avio_alloc_context()\n";
 return false;
 }

 pAVFormatContext->pb = pAVIOContext;
 pAVFormatContext->flags = AVFMT_FLAG_CUSTOM_IO; // - NOT SURE ABOUT THIS FLAG

 // Handle ffmpeg input
 //--------------------
 AVDictionary* options_in = NULL;
 //av_dict_set(&options_in, "framerate", "30", 0);
 av_dict_set(&options_in, "video_size", "1920x1080", 0);
 av_dict_set(&options_in, "pixel_format", "yuv420p", 0);
 av_dict_set(&options_in, "vcodec", "rawvideo", 0);

 if ((ret = avformat_open_input(&pAVFormatContext, "IO", NULL, &options_in) < 0) )
 {
 printf ("err=%d\n", ret);
 av_strerror(ret, errbuf, sizeof(errbuf));
 fprintf(stderr, "Unable to open err=%s\n", errbuf);
 return false;
 }

 //Raw video doesn't contain any stream information.
 //if ((ret = avformat_find_stream_info(pAVFormatContext, 0)) < 0) {
 // fprintf(stderr, "Failed to retrieve input stream information");
 //}

 AVCodec* pAVCodec = avcodec_find_decoder(AV_CODEC_ID_RAWVIDEO); //Get pointer to rawvideo codec.

 AVCodecContext* pAVCodecContext = avcodec_alloc_context3(pAVCodec); //Allocate codec context.

 //Fill the codec context based on the values from the codec parameters.
 AVStream *vid_stream = pAVFormatContext->streams[0];
 avcodec_parameters_to_context(pAVCodecContext, vid_stream->codecpar);

 avcodec_open2(pAVCodecContext, pAVCodec, NULL); //Open the codec

 //Allocate memory for packet and frame
 AVPacket* pAVPacketIn = av_packet_alloc();
 AVFrame* pAVFrameOut = av_frame_alloc();

 /* find the mpeg1video encoder */
 AVCodec* pAVCodecOut = avcodec_find_encoder_by_name("libx264");
 if (!pAVCodecOut) {
 fprintf(stderr, "Codec '%s' not found\n", "libx264");
 exit(1);
 }

 AVCodecContext* pAVCodecContextOut = avcodec_alloc_context3(pAVCodecOut);
 if (!pAVCodecContextOut) {
 fprintf(stderr, "Could not allocate video codec context\n");
 exit(1);
 }

 AVPacket* pAVPacketOut = av_packet_alloc();
 if (!pAVPacketOut)
 exit(1);

 /* put sample parameters */
 pAVCodecContextOut->bit_rate = 2000000;
 /* resolution must be a multiple of two */
 pAVCodecContextOut->width = 1280;
 pAVCodecContextOut->height = 720;
 /* frames per second */
 pAVCodecContextOut->time_base = (AVRational){1, 30};
 pAVCodecContextOut->framerate = (AVRational){30, 1};

 /* emit one intra frame every ten frames
 * check frame pict_type before passing frame
 * to encoder, if frame->pict_type is AV_PICTURE_TYPE_I
 * then gop_size is ignored and the output of encoder
 * will always be I frame irrespective to gop_size
 */
 pAVCodecContextOut->gop_size = 10;
 pAVCodecContextOut->max_b_frames = 0;
 pAVCodecContextOut->pix_fmt = AV_PIX_FMT_YUV420P;

 if (pAVCodecOut->id == AV_CODEC_ID_H264)
 av_opt_set(pAVCodecContextOut->priv_data, "preset", "slow", 0);

 /* open it */
 ret = avcodec_open2(pAVCodecContextOut, pAVCodecOut, NULL);
 if (ret < 0) {
 //fprintf(stderr, "Could not open codec: %s\n", av_err2str(ret));
 exit(1);
 }

 FILE* filename_out = fopen("out_vid_h264.mp4", "wb");
 if (!filename_out) {
 fprintf(stderr, "Could not open %s\n", "out_vid_h264.mp4");
 exit(1);
 }

 pAVFrameOut->format = pAVCodecContextOut->pix_fmt;
 pAVFrameOut->width = pAVCodecContextOut->width;
 pAVFrameOut->height = pAVCodecContextOut->height;


 uint8_t endcode_suf[] = { 0, 0, 1, 0xb7 };
 int i = 0;
 //Read video frames and pass through the decoder.
 //Note: Since the video is rawvideo, we don't really have to pass it through the decoder.
 while (av_read_frame(pAVFormatContext, pAVPacketIn) >= 0)
 {
 //The video is not encoded - passing through the decoder is simply copy the data.
 avcodec_send_packet(pAVCodecContext, pAVPacketIn); //Supply raw packet data as input to the "decoder".
 avcodec_receive_frame(pAVCodecContext, pAVFrameOut); //Return decoded output data from the "decoder".

 fflush(stdout);

 pAVFrameOut->pts = i++;

 /* encode the image */
 encode(pAVCodecContextOut, pAVFrameOut, pAVPacketOut, filename_out);
 }

 /* flush the encoder */
 encode(pAVCodecContextOut, NULL, pAVPacketOut, filename_out);

 /* Add sequence end code to have a real MPEG file.
 It makes only sense because this tiny examples writes packets
 directly. This is called "elementary stream" and only works for some
 codecs. To create a valid file, you usually need to write packets
 into a proper file format or protocol; see mux.c.
 */
 if (pAVCodecOut->id == AV_CODEC_ID_MPEG1VIDEO || pAVCodecOut->id == AV_CODEC_ID_MPEG2VIDEO)
 fwrite(endcode_suf, 1, sizeof(endcode_suf), filename_out);
 fclose(filename_out);


 return 0;
}
</iostream>

The output


./ffmpeg_custom_io 
Start reading custom IO
min buf size:32768
ptr:0x7f236a200000 size:933120000
End reading custom IO
Probing adp score:25 size:2048
Probing adp score:25 size:4096
Probing adp score:25 size:8192
Probing adp score:25 size:16384
Start reading custom IO
min buf size:32768
ptr:0x7f236a208000 size:933087232
End reading custom IO
Start reading custom IO
min buf size:65536
ptr:0x7f236a210000 size:933054464
End reading custom IO
Start reading custom IO
min buf size:131072
ptr:0x7f236a220000 size:932988928
End reading custom IO
Start reading custom IO
min buf size:262144
ptr:0x7f236a240000 size:932857856
End reading custom IO
Start reading custom IO
min buf size:524288
ptr:0x7f236a280000 size:932595712
End reading custom IO
err=1
Unable to open err=Error number 1 occurred



I tried all as noted above expecting avformat_open_input() will succeed, but it failed.


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ffmpeg (libav, libavfilter, etx) - modify frame with image or text using C\C++ API
7 juillet 2023, par AlexAfter reading a huge bunch of docs and tutorials I still cant find a way to add some image or text to each frame of video. Something like logo on the frame corner, or text watermark.


Iam know how to do such things with ffmpeg from cli, but for this case, C\C++ code is required.


Looks like, ffmpeg's libav allow me to do some things with frame on decode stage, using AVFrame structure of current frame and add some modifications to it with libavfilter. But how exactly this can be done ?


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