avcodec_send_frame returns "invalid argument" - c++

Question

I'm trying to direct the output from opengl into a mp4 file.
Currently, I'm getting the error "Invalid input" from the call avcodec_send_frame(c, frame). Why am I getting this error?
class VideoCapture2
{
public:
VideoCapture2(const char *filename, unsigned int width, unsigned int height, int framerate, unsigned int bitrate){
avformat_alloc_output_context2(&avFormatContext, NULL, NULL, filename);
if (!avFormatContext) {
printf("Could not deduce output format from file extension: using MPEG.\n");
avformat_alloc_output_context2(&avFormatContext, NULL, "mpeg", filename);
}
if (!avFormatContext)
exit(1);
avOutputFormat = avFormatContext->oformat;
// Video Stream
/* find the encoder */
AVCodecID codec_id = AV_CODEC_ID_H264;
codec = avcodec_find_encoder(codec_id);
if (!codec) {
fprintf(stderr, "Could not find encoder for '%s'\n",
avcodec_get_name(codec_id));
exit(1);
}
pkt = av_packet_alloc();
if (!pkt) {
fprintf(stderr, "Could not allocate AVPacket\n");
exit(1);
}
avStream = avformat_new_stream(avFormatContext, NULL);
if (!avStream) {
fprintf(stderr, "Could not allocate stream\n");
exit(1);
}
avStream->id = avFormatContext->nb_streams-1;
codec_ctx = avcodec_alloc_context3(codec);
if (!codec_ctx) {
fprintf(stderr, "Could not alloc an encoding context\n");
exit(1);
}
codec_ctx->codec_id = codec_id;
/* put sample parameters */
codec_ctx->bit_rate = bitrate;
/* resolution must be a multiple of two */
if(width % 2 != 0)
throw std::invalid_argument( "The width must be devisible by two" );
if(height % 2 != 0)
throw std::invalid_argument( "The height must be devisible by two" );
codec_ctx->width = width;
codec_ctx->height = height;
/* frames per second */
codec_ctx->framerate = (AVRational){framerate, 1};
/* timebase: This is the fundamental unit of time (in seconds) in terms
* of which frame timestamps are represented. For fixed-fps content,
* timebase should be 1/framerate and timestamp increments should be
* identical to 1. */
avStream->time_base = (AVRational){ 1, framerate };
codec_ctx->time_base = avStream->time_base;
codec_ctx->gop_size = 10; /* emit one intra frame every twelve frames at most */
codec_ctx->pix_fmt = AV_PIX_FMT_YUV420P;
/* Some formats want stream headers to be separate. */
if (avOutputFormat->flags & AVFMT_GLOBALHEADER)
codec_ctx->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
frame = alloc_frame(codec_ctx->pix_fmt, codec_ctx->width, codec_ctx->height);
if (!frame) {
fprintf(stderr, "Could not allocate video frame\n");
exit(1);
}
/* copy the stream parameters to the muxer */
ret = avcodec_parameters_from_context(avStream->codecpar, codec_ctx);
if (ret < 0) {
fprintf(stderr, "Could not copy the stream parameters\n");
exit(1);
}
// Color format Conversion
sws = sws_getContext( codec_ctx->width
, codec_ctx->height
, AV_PIX_FMT_RGB32
, codec_ctx->width
, codec_ctx->height
, AV_PIX_FMT_YUV420P
, SWS_FAST_BILINEAR // Change this???
, 0, 0, 0);
// Check output file
av_dump_format(avFormatContext, 0, filename, 1);
/* open the output file, if needed */
if (!(avOutputFormat->flags & AVFMT_NOFILE)) {
ret = avio_open(&avFormatContext->pb, filename, AVIO_FLAG_WRITE);
if (ret < 0) {
fprintf(stderr, "Could not open '%s': %s\n", filename,
av_err2str(ret));
exit(1);
}
}
/* Write the stream header, if any. */
ret = avformat_write_header(avFormatContext, &avDict);
if (ret < 0) {
fprintf(stderr, "Error occurred when opening output file: %s\n",
av_err2str(ret));
exit(1);
}
}
void addFrame(){
fflush(stdout);
/* Make sure the frame data is writable.
On the first round, the frame is fresh from av_frame_get_buffer()
and therefore we know it is writable.
But on the next rounds, encode() will have called
avcodec_send_frame(), and the codec may have kept a reference to
the frame in its internal structures, that makes the frame
unwritable.
av_frame_make_writable() checks that and allocates a new buffer
for the frame only if necessary.
*/
ret = av_frame_make_writable(frame);
if (ret < 0){
fprintf(stderr, "Could not make the frame writable\n");
exit(1); // Wait... you should throw error instead!
}
size_t nvals = 4 * codec_ctx->width * codec_ctx->height; //GL_BGRA
pixels = (GLubyte *) realloc(pixels, nvals * sizeof(GLubyte)); // I don't think I need to do this every time since the size is constant
glReadPixels(0, 0, codec_ctx->width, codec_ctx->height, GL_BGRA, GL_UNSIGNED_BYTE, pixels);
// CONVERT TO YUV AND ENCODE
ret = av_image_alloc(frame->data, frame->linesize, codec_ctx->width, codec_ctx->height, AV_PIX_FMT_YUV420P, 32);
if (ret < 0){
fprintf(stderr, "Could not allocate the image\n");
exit(1); // Wait... you should throw error instead!
}
// Compensate for OpenGL y-axis pointing upwards and ffmpeg y-axis pointing downwards
uint8_t *in_data[1] = {(uint8_t *) pixels + (codec_ctx->height-1)*codec_ctx->width*4}; // address of the last line
int in_linesize[1] = {- codec_ctx->width * 4}; // negative stride
sws_scale(sws, in_data, in_linesize, 0, codec_ctx->height, frame->data, frame->linesize);
frame->pts = frame_order;
frame_order++;
/* encode the image */
write_frame(avFormatContext, codec_ctx, avStream, frame, pkt);
}
void close()
{
write_frame(avFormatContext, codec_ctx, avStream, NULL, pkt);
av_write_trailer(avFormatContext);
avcodec_free_context(&codec_ctx);
av_frame_free(&frame);
sws_freeContext(sws);
if (!(avFormatContext->oformat->flags & AVFMT_NOFILE))
/* Close the output file. */
avio_closep(&avFormatContext->pb);
avformat_free_context(avFormatContext);
}
private:
AVOutputFormat *avOutputFormat;
AVFormatContext* avFormatContext = NULL;
AVStream* avStream;
AVDictionary *avDict = NULL; // "create" an empty dictionary
GLubyte *pixels = NULL;
struct SwsContext *sws;
const AVCodec *codec;
AVCodecContext *codec_ctx= NULL;
// Should be ref counted??? https://ffmpeg.org/doxygen/3.3/group__lavc__encdec.html
AVFrame *frame;
AVPacket *pkt;
//
int frame_order, ret;
int write_frame(AVFormatContext *fmt_ctx, AVCodecContext *c,
AVStream *st, AVFrame *frame, AVPacket *pkt)
{
int ret;
// ERROR OCCURS HERE
ret = avcodec_send_frame(c, frame);
// ERROR OCCURS HERE
if (ret < 0) {
fprintf(stderr, "Error sending a frame to the encoder: %s\n",
av_err2str(ret));
exit(1);
}
while (ret >= 0) {
ret = avcodec_receive_packet(c, pkt);
if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
break;
else if (ret < 0) {
fprintf(stderr, "Error encoding a frame: %s\n", av_err2str(ret));
exit(1);
}
/* rescale output packet timestamp values from codec to stream timebase */
av_packet_rescale_ts(pkt, c->time_base, st->time_base);
pkt->stream_index = st->index;
/* Write the compressed frame to the media file. */
log_packet(fmt_ctx, pkt);
ret = av_interleaved_write_frame(fmt_ctx, pkt);
/* pkt is now blank (av_interleaved_write_frame() takes ownership of
* its contents and resets pkt), so that no unreferencing is necessary.
* This would be different if one used av_write_frame(). */
if (ret < 0) {
fprintf(stderr, "Error while writing output packet: %s\n", av_err2str(ret));
exit(1);
}
}
return ret == AVERROR_EOF ? 1 : 0;
}
void log_packet(const AVFormatContext *fmt_ctx, const AVPacket *pkt)
{
AVRational *time_base = &fmt_ctx->streams[pkt->stream_index]->time_base;
printf("pts:%s pts_time:%s dts:%s dts_time:%s duration:%s duration_time:%s stream_index:%d\n",
av_ts2str(pkt->pts), av_ts2timestr(pkt->pts, time_base),
av_ts2str(pkt->dts), av_ts2timestr(pkt->dts, time_base),
av_ts2str(pkt->duration), av_ts2timestr(pkt->duration, time_base),
pkt->stream_index);
}
AVFrame *alloc_frame(enum AVPixelFormat pix_fmt, int width, int height)
{
AVFrame *frame;
int ret;
frame = av_frame_alloc();
if (!frame)
return NULL;
frame->format = pix_fmt;
frame->width = width;
frame->height = height;
/* allocate the buffers for the frame data */
ret = av_frame_get_buffer(frame, 0);
if (ret < 0) {
fprintf(stderr, "Could not allocate frame data.\n");
exit(1);
}
return frame;
}
};

Answer 1

The issue turned out to be that I had missed calling avcodec_open2(..) now it works :)
/* open the codec */
AVDictionary *opt = NULL;
av_dict_copy(&opt, avDict, 0);
ret = avcodec_open2(codec_ctx, codec, &opt);
av_dict_free(&opt);
if (ret < 0) {
fprintf(stderr, "Could not open video codec: %s\n", av_err2str(ret));
exit(1);
}
// Then allocate frame...
frame = alloc_frame(codec_ctx->pix_fmt, codec_ctx->width, codec_ctx->height);
if (!frame) {
fprintf(stderr, "Could not allocate video frame\n");
exit(1);
}
For reference, this is the full code (but the video quality is shit so you will have to tune that yourself)
#ifndef VIDEO_CAPTURE2_H
#define VIDEO_CAPTURE2_H
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "../include/glad/glad.h"
#include "finite_math.hpp"
#include <stdexcept>
extern "C" {
#include <libavcodec/avcodec.h>
#include <libswscale/swscale.h>
#include <libavutil/opt.h>
#include <libavutil/imgutils.h>
#include <libavformat/avformat.h>
#include <libavutil/opt.h>
#include <libavutil/mathematics.h>
#include <libavutil/timestamp.h>
}
// These exist to patch three functions for which gcc gets compiler errors
#ifdef av_err2str
#undef av_err2str
#include <string>
av_always_inline std::string av_err2string(int errnum) {
char str[AV_ERROR_MAX_STRING_SIZE];
return av_make_error_string(str, AV_ERROR_MAX_STRING_SIZE, errnum);
}
#define av_err2str(err) av_err2string(err).c_str()
#endif
#ifdef av_ts2str
#undef av_ts2str
#include <string>
av_always_inline std::string av_ts2string(int ts) {
char str[AV_TS_MAX_STRING_SIZE];
return av_ts_make_string(str, ts);
}
#define av_ts2str(ts) av_ts2string(ts).c_str()
#endif
#ifdef av_ts2timestr
#undef av_ts2timestr
#include <string>
av_always_inline std::string av_ts2timestring(int ts, AVRational *tb) {
char str[AV_TS_MAX_STRING_SIZE];
return av_ts_make_time_string(str, ts, tb);
}
#define av_ts2timestr(ts, tb) av_ts2timestring(ts, tb).c_str()
#endif
class VideoCapture2
{
public:
VideoCapture2(const char *filename, unsigned int width, unsigned int height, int framerate, unsigned int bitrate){
avformat_alloc_output_context2(&avFormatContext, NULL, NULL, filename);
if (!avFormatContext) {
printf("Could not deduce output format from file extension: using MPEG.\n");
avformat_alloc_output_context2(&avFormatContext, NULL, "mpeg", filename);
}
if (!avFormatContext)
exit(1);
avOutputFormat = avFormatContext->oformat;
// Video Stream
/* find the mpeg1video encoder */
/* find the encoder */
AVCodecID codec_id = AV_CODEC_ID_H264;
codec = avcodec_find_encoder(codec_id);
if (!codec) {
fprintf(stderr, "Could not find encoder for '%s'\n",
avcodec_get_name(codec_id));
exit(1);
}
pkt = av_packet_alloc();
if (!pkt) {
fprintf(stderr, "Could not allocate AVPacket\n");
exit(1);
}
avStream = avformat_new_stream(avFormatContext, NULL);
if (!avStream) {
fprintf(stderr, "Could not allocate stream\n");
exit(1);
}
avStream->id = avFormatContext->nb_streams-1;
codec_ctx = avcodec_alloc_context3(codec);
if (!codec_ctx) {
fprintf(stderr, "Could not alloc an encoding context\n");
exit(1);
}
codec_ctx->codec_id = codec_id;
/* put sample parameters */
codec_ctx->bit_rate = bitrate;
/* resolution must be a multiple of two */
if(width % 2 != 0)
throw std::invalid_argument( "The width must be devisible by two" );
if(height % 2 != 0)
throw std::invalid_argument( "The height must be devisible by two" );
codec_ctx->width = width;
codec_ctx->height = height;
/* frames per second */
codec_ctx->framerate = (AVRational){framerate, 1};
/* timebase: This is the fundamental unit of time (in seconds) in terms
* of which frame timestamps are represented. For fixed-fps content,
* timebase should be 1/framerate and timestamp increments should be
* identical to 1. */
avStream->time_base = (AVRational){ 1, framerate };
codec_ctx->time_base = avStream->time_base;
codec_ctx->gop_size = 10; /* emit one intra frame every twelve frames at most */
codec_ctx->pix_fmt = AV_PIX_FMT_YUV420P;
/* Some formats want stream headers to be separate. */
if (avOutputFormat->flags & AVFMT_GLOBALHEADER)
codec_ctx->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
/* open the codec */
AVDictionary *opt = NULL;
av_dict_copy(&opt, avDict, 0);
ret = avcodec_open2(codec_ctx, codec, &opt);
av_dict_free(&opt);
if (ret < 0) {
fprintf(stderr, "Could not open video codec: %s\n", av_err2str(ret));
exit(1);
}
frame = alloc_frame(codec_ctx->pix_fmt, codec_ctx->width, codec_ctx->height);
if (!frame) {
fprintf(stderr, "Could not allocate video frame\n");
exit(1);
}
/* copy the stream parameters to the muxer */
ret = avcodec_parameters_from_context(avStream->codecpar, codec_ctx);
if (ret < 0) {
fprintf(stderr, "Could not copy the stream parameters\n");
exit(1);
}
// Color fromat COnversion
sws = sws_getContext( codec_ctx->width
, codec_ctx->height
, AV_PIX_FMT_RGB32
, codec_ctx->width
, codec_ctx->height
, AV_PIX_FMT_YUV420P
, SWS_FAST_BILINEAR // Change this???
, 0, 0, 0);
// Check output file
av_dump_format(avFormatContext, 0, filename, 1);
/* open the output file, if needed */
if (!(avOutputFormat->flags & AVFMT_NOFILE)) {
ret = avio_open(&avFormatContext->pb, filename, AVIO_FLAG_WRITE);
if (ret < 0) {
fprintf(stderr, "Could not open '%s': %s\n", filename,
av_err2str(ret));
exit(1);
}
}
/* Write the stream header, if any. */
ret = avformat_write_header(avFormatContext, &avDict);
if (ret < 0) {
fprintf(stderr, "Error occurred when opening output file: %s\n",
av_err2str(ret));
exit(1);
}
}
void addFrame(){
fflush(stdout);
/* Make sure the frame data is writable.
On the first round, the frame is fresh from av_frame_get_buffer()
and therefore we know it is writable.
But on the next rounds, encode() will have called
avcodec_send_frame(), and the codec may have kept a reference to
the frame in its internal structures, that makes the frame
unwritable.
av_frame_make_writable() checks that and allocates a new buffer
for the frame only if necessary.
*/
ret = av_frame_make_writable(frame);
if (ret < 0){
fprintf(stderr, "Could not make the frame writable\n");
exit(1); // Wait... you should throw error instead!
}
size_t nvals = 4 * codec_ctx->width * codec_ctx->height; //GL_BGRA
pixels = (GLubyte *) realloc(pixels, nvals * sizeof(GLubyte)); // I don't think I need to do this every time since the size is constant
glReadPixels(0, 0, codec_ctx->width, codec_ctx->height, GL_BGRA, GL_UNSIGNED_BYTE, pixels);
// CONVERT TO YUV AND ENCODE
ret = av_image_alloc(frame->data, frame->linesize, codec_ctx->width, codec_ctx->height, AV_PIX_FMT_YUV420P, 32);
if (ret < 0){
fprintf(stderr, "Could not allocate the image\n");
exit(1); // Wait... you should throw error instead!
}
// Compensate for OpenGL y-axis pointing upwards and ffmpeg y-axis pointing downwards
uint8_t *in_data[1] = {(uint8_t *) pixels + (codec_ctx->height-1)*codec_ctx->width*4}; // address of the last line
int in_linesize[1] = {- codec_ctx->width * 4}; // negative stride
sws_scale(sws, in_data, in_linesize, 0, codec_ctx->height, frame->data, frame->linesize);
frame->pts = frame_order;
frame_order++;
/* encode the image */
write_frame(avFormatContext, codec_ctx, avStream, frame, pkt);
}
void close()
{
write_frame(avFormatContext, codec_ctx, avStream, NULL, pkt);
av_write_trailer(avFormatContext);
avcodec_free_context(&codec_ctx);
av_frame_free(&frame);
sws_freeContext(sws);
if (!(avFormatContext->oformat->flags & AVFMT_NOFILE))
/* Close the output file. */
avio_closep(&avFormatContext->pb);
avformat_free_context(avFormatContext);
}
private:
AVOutputFormat *avOutputFormat;
AVFormatContext* avFormatContext = NULL;
AVStream* avStream;
AVDictionary *avDict = NULL; // "create" an empty dictionary
GLubyte *pixels = NULL;
struct SwsContext *sws;
const AVCodec *codec;
AVCodecContext *codec_ctx= NULL;
// Should be ref counted??? https://ffmpeg.org/doxygen/3.3/group__lavc__encdec.html
AVFrame *frame;
AVPacket *pkt;
//
int frame_order, ret;
int write_frame(AVFormatContext *fmt_ctx, AVCodecContext *c,
AVStream *st, AVFrame *frame, AVPacket *pkt)
{
int ret;
// send the frame to the encoder
ret = avcodec_send_frame(c, frame);
if (ret < 0) {
fprintf(stderr, "Error sending a frame to the encoder: %s\n",
av_err2str(ret));
exit(1);
}
while (ret >= 0) {
ret = avcodec_receive_packet(c, pkt);
if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
break;
else if (ret < 0) {
fprintf(stderr, "Error encoding a frame: %s\n", av_err2str(ret));
exit(1);
}
/* rescale output packet timestamp values from codec to stream timebase */
av_packet_rescale_ts(pkt, c->time_base, st->time_base);
pkt->stream_index = st->index;
/* Write the compressed frame to the media file. */
log_packet(fmt_ctx, pkt);
ret = av_interleaved_write_frame(fmt_ctx, pkt);
/* pkt is now blank (av_interleaved_write_frame() takes ownership of
* its contents and resets pkt), so that no unreferencing is necessary.
* This would be different if one used av_write_frame(). */
if (ret < 0) {
fprintf(stderr, "Error while writing output packet: %s\n", av_err2str(ret));
exit(1);
}
}
return ret == AVERROR_EOF ? 1 : 0;
}
void log_packet(const AVFormatContext *fmt_ctx, const AVPacket *pkt)
{
AVRational *time_base = &fmt_ctx->streams[pkt->stream_index]->time_base;
printf("pts:%s pts_time:%s dts:%s dts_time:%s duration:%s duration_time:%s stream_index:%d\n",
av_ts2str(pkt->pts), av_ts2timestr(pkt->pts, time_base),
av_ts2str(pkt->dts), av_ts2timestr(pkt->dts, time_base),
av_ts2str(pkt->duration), av_ts2timestr(pkt->duration, time_base),
pkt->stream_index);
}
AVFrame *alloc_frame(enum AVPixelFormat pix_fmt, int width, int height)
{
AVFrame *frame;
int ret;
frame = av_frame_alloc();
if (!frame)
return NULL;
frame->format = pix_fmt;
frame->width = width;
frame->height = height;
/* allocate the buffers for the frame data */
ret = av_frame_get_buffer(frame, 0);
if (ret < 0) {
fprintf(stderr, "Could not allocate frame data.\n");
exit(1);
}
return frame;
}
};
#endif