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私のC++アプリケーションでは、一連のJPEG画像を取得し、FreeImageを使用してデータを操作してから、ffmpeg/libx264 C APIを使用してビットマップをH264としてエンコードします。出力はMP4で、12fpsで一連の22枚の画像が表示されます。私のコードは、ffmpegのCソースコードに付属している "多重化"の例に適合しています。ffmpeg/libx264 C API：ショートMP4の終わりからフレームがドロップ
私の問題：どのようにコーデックのパラメータを調整しても、エンコーダに渡されるシーケンスの最後の特定の数のフレームが最終出力に現れません。私はこのようなAVCodecContextパラメータを設定している：私が見つけた
//set context params
ctx->codec_id = AV_CODEC_ID_H264;
ctx->bit_rate = 4000 * 1000;
ctx->width = _width;
ctx->height = _height;
ost->st->time_base = AVRational{ 1, 12 };
ctx->time_base = ost->st->time_base;
ctx->gop_size = 1;
ctx->pix_fmt = AV_PIX_FMT_YUV420P;
それ以上のフレームは、ビデオの最後から削除されgop_sizeを高いです。私は出力から、このgopサイズ（基本的には、すべての出力フレームをIフレームとしている）を見ると、9フレームしか書き込まれていないことが分かります。
これがなぜ発生しているのかわかりません。私は重複したフレームをエンコードし、はるかに長いビデオを作ることを実験しました。その結果、フレームがドロップされませんでした。私はffmpegコマンドラインツールで、私がしようとしていることを達成する連結コマンドがあることは知っていますが、C APIを使用して同じ目標を達成する方法がわかりません。ここで
は、私は、コンソールから取得していた出力です：
[libx264 @ 026d81c0] CPUの機能を使用して：MMX2 SSE2Fast SSSE3を SSE4.2 AVX FMA3 BMI2 AVX2 [libx264 @ 026d81c0]ハイプロファイル、レベル 3.1 [libx264 @ 026d81c0] 264 - コア152 r2851 ba24899 - H.264/MPEG-4 AVCコーデック - Cop yleft 2003-2017 - http://www.videolan.org/x264.html - オプション：cabac = 1 ref = 1 debロック= 1：0：0 analyze 0x3：0x113 me = hex subme = 7 psy = 1 psy_rd = 1.00：0.00 mixed_ref = 0 m e_range = 16 chroma_me = 1トレリス= 1 8x8dct = 1 cqm = 0 deadzone = 21,11 fast_pskip = 1 chro ma_qp_offset = -2 インターレース= 0 bluray_compat = 0 bframes = 0 weightp = 0 keyint = 1 ke yint_min = 1 scenecut = 40 intra_refresh = 0 rc = abr mbtree = 0 bitrate = 4000 ratetol = 1.0 qcomp = 0.60 qpmin = 0 qpmax = 69 qpstep = 4 ip_ratio = 1.40 aq = 1：1.00出力＃0、mp4から '.... \ images \ c411a991-46f6- 400C-8bb0-77af3738559a.mp4' ストリーム＃0：0：ビデオ：H264、YUV420P、700x700、Q = 2-31、4000キロバイト/秒、12 TBN
[libx264 @ 026d81c0]フレームI：9平均QP：17.83サイズ：111058 [libx264 @ 026d81c0] mb I 16.4：1.9％47.7％50.5％[libx264 @ 026d81c0] final ratefactor：19.14 [libx264 @ 026d81c0] 8 x8変換イントラ：47.7％ [libx264 @ 026d81c0]コード化y、uvDC、uvACイントラ：98.4％96.9％89.5％ [libx264 @ 026d81c0] i16v、h、dc、p：64％6％2％28％ [libx264 @ 0126d81c0] i4 viii、v1、v2、h3、v2、h3、v2、v3、v4、 h、v、hu：28％18％012％16％8％8％8％8％9％8％ 43％22％ 25％、10％[libx264 @は026d81c0] KB/S：10661.53
コードは以下を含む：
MP4Writer.h
#ifndef MPEG_WRITER
#define MPEG_WRITER
#include <iostream>
#include <string>
#include <vector>
#include <ImgData.h>
extern "C" {
#include <libavformat/avformat.h>
#include <libswscale/swscale.h>
#include <libswresample/swresample.h>
#include <libswscale/swscale.h>
}
typedef struct OutputStream
{
AVStream *st;
AVCodecContext *enc;
//pts of the next frame that will be generated
int64_t next_pts;
int samples_count;
AVFrame *frame;
AVFrame *tmp_frame;
float t, tincr, tincr2;
struct SwsContext *sws_ctx;
struct SwrContext *swr_ctx;
};
class MP4Writer {
public:
MP4Writer();
void Init();
int16_t SetOutput(const std::string & path);
int16_t AddFrame(uint8_t * imgData);
int16_t Write(std::vector<ImgData> & imgData);
int16_t Finalize();
void SetHeight(const int height) { _height = _width = height; } //assuming 1:1 aspect ratio
private:
int16_t AddStream(OutputStream * ost, AVFormatContext * formatCtx, AVCodec ** codec, enum AVCodecID codecId);
int16_t OpenVideo(AVFormatContext * formatCtx, AVCodec *codec, OutputStream * ost, AVDictionary * optArg);
static AVFrame * AllocPicture(enum AVPixelFormat pixFmt, int width, int height);
static AVFrame * GetVideoFrame(uint8_t * imgData, OutputStream * ost, const int width, const int height);
static int WriteFrame(AVFormatContext * formatCtx, const AVRational * timeBase, AVStream * stream, AVPacket * packet);
int _width;
int _height;
OutputStream _ost;
AVFormatContext * _formatCtx;
AVDictionary * _dict;
};
#endif //MPEG_WRITER
MP4Writer。CPP
#include <MP4Writer.h>
#include <algorithm>
MP4Writer::MP4Writer()
{
_width = 0;
_height = 0;
}
void MP4Writer::Init()
{
av_register_all();
}
/**
sets up output stream for the specified path.
note that the output format is deduced automatically from the file extension passed
@param path: output file path
@returns: -1 = output could not be deduced, -2 = invalid codec, -3 = error opening output file,
-4 = error writing header
*/
int16_t MP4Writer::SetOutput(const std::string & path)
{
int error;
AVCodec * codec;
AVOutputFormat * format;
_ost = OutputStream{}; //TODO reset state in a more focused way?
//allocate output media context
avformat_alloc_output_context2(&_formatCtx, NULL, NULL, path.c_str());
if (!_formatCtx) {
std::cout << "could not deduce output format from file extension. aborting" << std::endl;
return -1;
}
//set format
format = _formatCtx->oformat;
if (format->video_codec != AV_CODEC_ID_NONE) {
AddStream(&_ost, _formatCtx, &codec, format->video_codec);
}
else {
std::cout << "there is no video codec set. aborting" << std::endl;
return -2;
}
OpenVideo(_formatCtx, codec, &_ost, _dict);
av_dump_format(_formatCtx, 0, path.c_str(), 1);
//open output file
if (!(format->flags & AVFMT_NOFILE)) {
error = avio_open(&_formatCtx->pb, path.c_str(), AVIO_FLAG_WRITE);
if (error < 0) {
std::cout << "there was an error opening output file " << path << ". aborting" << std::endl;
return -3;
}
}
//write header
error = avformat_write_header(_formatCtx, &_dict);
if (error < 0) {
std::cout << "an error occurred writing header. aborting" << std::endl;
return -4;
}
return 0;
}
/**
initialize the output stream
@param ost: the output stream
@param formatCtx: the context format
@param codec: the output codec
@param codec: the ffmpeg enumerated id of the codec
@returns: -1 = encoder not found, -2 = stream could not be allocated, -3 = encoding context could not be allocated
*/
int16_t MP4Writer::AddStream(OutputStream * ost, AVFormatContext * formatCtx, AVCodec ** codec, enum AVCodecID codecId)
{
AVCodecContext * ctx; //TODO not sure why this is here, could just set ost->enc directly
int i;
//detect the encoder
*codec = avcodec_find_encoder(codecId);
if ((*codec) == NULL) {
std::cout << "could not find encoder. aborting" << std::endl;
return -1;
}
//allocate stream
ost->st = avformat_new_stream(formatCtx, NULL);
if (ost->st == NULL) {
std::cout << "could not allocate stream. aborting" << std::endl;
return -2;
}
//allocate encoding context
ost->st->id = formatCtx->nb_streams - 1;
ctx = avcodec_alloc_context3(*codec);
if (ctx == NULL) {
std::cout << "could not allocate encoding context. aborting" << std::endl;
return -3;
}
ost->enc = ctx;
//set context params
ctx->codec_id = AV_CODEC_ID_H264;
ctx->bit_rate = 4000 * 1000;
ctx->width = _width;
ctx->height = _height;
ost->st->time_base = AVRational{ 1, 12 };
ctx->time_base = ost->st->time_base;
ctx->gop_size = 1;
ctx->pix_fmt = AV_PIX_FMT_YUV420P;
//if neccesary, set stream headers and formats separately
if (formatCtx->oformat->flags & AVFMT_GLOBALHEADER) {
std::cout << "setting stream and headers to be separate" << std::endl;
ctx->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
}
return 0;
}
/**
open the video for writing
@param formatCtx: the format context
@param codec: output codec
@param ost: output stream
@param optArg: dictionary
@return: -1 = error opening codec, -2 = allocate new frame, -3 = copy stream params
*/
int16_t MP4Writer::OpenVideo(AVFormatContext * formatCtx, AVCodec *codec, OutputStream * ost, AVDictionary * optArg)
{
int error;
AVCodecContext * ctx = ost->enc;
AVDictionary * dict = NULL;
av_dict_copy(&dict, optArg, 0);
//open codec
error = avcodec_open2(ctx, codec, &dict);
av_dict_free(&dict);
if (error < 0) {
std::cout << "there was an error opening the codec. aborting" << std::endl;
return -1;
}
//allocate new frame
ost->frame = AllocPicture(ctx->pix_fmt, ctx->width, ctx->height);
if (ost->frame == NULL) {
std::cout << "there was an error allocating a new frame. aborting" << std::endl;
return -2;
}
//copy steam params
error = avcodec_parameters_from_context(ost->st->codecpar, ctx);
if (error < 0) {
std::cout << "could not copy stream parameters. aborting" << std::endl;
return -3;
}
return 0;
}
/**
allocate a new frame
@param pixFmt: ffmpeg enumerated pixel format
@param width: output width
@param height: output height
@returns: an inititalized frame
*/
AVFrame * MP4Writer::AllocPicture(enum AVPixelFormat pixFmt, int width, int height)
{
AVFrame * picture;
int error;
//allocate the frame
picture = av_frame_alloc();
if (picture == NULL) {
std::cout << "there was an error allocating the picture" << std::endl;
return NULL;
}
picture->format = pixFmt;
picture->width = width;
picture->height = height;
//allocate the frame's data buffer
error = av_frame_get_buffer(picture, 32);
if (error < 0) {
std::cout << "could not allocate frame data" << std::endl;
return NULL;
}
picture->pts = 0;
return picture;
}
/**
convert raw RGB buffer to YUV frame
@return: frame that contains image data
*/
AVFrame * MP4Writer::GetVideoFrame(uint8_t * imgData, OutputStream * ost, const int width, const int height)
{
int error;
AVCodecContext * ctx = ost->enc;
//prepare the frame
error = av_frame_make_writable(ost->frame);
if (error < 0) {
std::cout << "could not make frame writeable" << std::endl;
return NULL;
}
//TODO set this context one time per run, or even better, one time at init
//convert RGB to YUV
struct SwsContext* fooContext = sws_getContext(width, height, AV_PIX_FMT_BGR24,
width, height, AV_PIX_FMT_YUV420P, SWS_BICUBIC, NULL, NULL, NULL);
int inLinesize[1] = { 3 * width }; // RGB stride
uint8_t * inData[1] = { imgData };
int sliceHeight = sws_scale(fooContext, inData, inLinesize, 0, height, ost->frame->data, ost->frame->linesize);
sws_freeContext(fooContext);
ost->frame->pts = ost->next_pts++;
//TODO does the frame need to be returned here as it is available at the class level?
return ost->frame;
}
/**
write frame to file
@param formatCtx: the output format context
@param timeBase: the framerate
@param stream: output stream
@param packet: data packet
@returns: see return values for av_interleaved_write_frame
*/
int MP4Writer::WriteFrame(AVFormatContext * formatCtx, const AVRational * timeBase, AVStream * stream, AVPacket * packet)
{
av_packet_rescale_ts(packet, *timeBase, stream->time_base);
packet->stream_index = stream->index;
//write compressed file to media file
return av_interleaved_write_frame(formatCtx, packet);
}
int16_t MP4Writer::Write(std::vector<ImgData> & imgData)
{
int16_t errorCount = 0;
int16_t retVal = 0;
bool countingUp = true;
size_t i = 0;
while (true) {
//don't show first frame again when counting back down
if (!countingUp && i == 0) {
break;
}
uint8_t * pixels = imgData[i].GetBits(imgData[i].mp4Input);
AddFrame(pixels);
//handle inc/dec without repeating last frame
if (countingUp) {
if (i == imgData.size() -1) {
countingUp = false;
i--;
}
else {
i++;
}
}
else {
i--;
}
}
Finalize();
return 0; //TODO return error code
}
/**
add another frame to output video
@param imgData: the raw image data
@returns -1 = error encoding video frame, -2 = error writing frame
*/
int16_t MP4Writer::AddFrame(uint8_t * imgData)
{
int error;
AVCodecContext * ctx;
AVFrame * frame;
int gotPacket = 0;
AVPacket pkt = { 0 };
ctx = _ost.enc;
av_init_packet(&pkt);
frame = GetVideoFrame(imgData, &_ost, _width, _height);
//encode the image
error = avcodec_encode_video2(ctx, &pkt, frame, &gotPacket);
if (error < 0) {
std::cout << "there was an error encoding the video frame" << std::endl;
return -1;
}
//write the frame. NOTE: this doesn't kick in until the encoder has received a certain number of frames
if (gotPacket) {
error = WriteFrame(_formatCtx, &ctx->time_base, _ost.st, &pkt);
if (error < 0) {
std::cout << "the video frame could not be written" << std::endl;
return -2;
}
}
return 0;
}
/**
finalize output video and cleanup
*/
int16_t MP4Writer::Finalize()
{
av_write_trailer(_formatCtx);
avcodec_free_context(&_ost.enc);
av_frame_free(&_ost.frame);
av_frame_free(&_ost.tmp_frame);
avio_closep(&_formatCtx->pb);
avformat_free_context(_formatCtx);
sws_freeContext(_ost.sws_ctx);
swr_free(&_ost.swr_ctx);
return 0;
}
使用量は
#include <FreeImage.h>
#include <MP4Writer.h>
#include <vector>
struct ImgData
{
unsigned int width;
unsigned int height;
std::string path;
FIBITMAP * mp4Input;
uint8_t * GetBits(FIBITMAP * bmp) { return FreeImage_GetBits(bmp); }
};
int main()
{
std::vector<ImgData> imgDataVec;
//load images and push to imgDataVec
MP4Writer mp4Writer;
mp4Writer.SetHeight(1200); //assumes 1:1 aspect ratio
mp4Writer.Init();
mp4Writer.SetOutput("test.mp4");
mp4Writer.Write(imgDataVec);
}
私のCコンパイラがこのコードを拒否すると思われます。 –
あなたは正しいですか：このコードはC++ –