H.264传输流的AVCODEC_DECODE_VIDEO2的内容
What to pass to avcodec_decode_video2 for H.264 Transport Stream?
我想从MPEG-2传输流数据包中解码H.264视频，但我不清楚该传递给avcodec_decode_video2
文档说要传递"包含输入缓冲区的输入AVPACKET"。
但是输入缓冲区中应该是什么？
PES数据包将分布在几个TS数据包的有效负载部分，而Nalu（s）内部是PES。那么通过TS碎片吗？整个pes？PES有效载荷？
此示例代码提到：
但是其他一些编解码器（MSMPEG4，MPEG4）固有地基于框架，因此 您必须将它们与所有数据完全拨打，以确切地将其调用。你必须 在初始化它们之前，还要初始化"宽度"answers"高度"。
但我找不到有关"所有数据"的信息...
传递TS数据包有效载荷的片段不起作用：
AVPacket avDecPkt;
av_init_packet(&avDecPkt);
avDecPkt.data = inbuf_ptr;
avDecPkt.size = esBufSize;
len = avcodec_decode_video2(mpDecoderContext, mpFrameDec, &got_picture, &avDecPkt);
if (len < 0)
{
printf(" TS PKT #%.0f. Error decoding frame #%04d [rc=%d '%s']n",
tsPacket.pktNum, mDecodedFrameNum, len, av_make_error_string(errMsg, 128, len));
return;
}
输出
[h264 @ 0x81cd2a0] no frame!
TS PKT #2973. Error decoding frame #0001 [rc=-1094995529 'Invalid data found when processing input']
编辑
使用WLGFX的出色命中，我制作了这个简单的程序来尝试解码TS数据包。作为输入，我准备了一个包含的文件，仅视频pid中的 ts数据包。
感觉很接近，但我不知道如何设置格式。AV_READ_FRAME（）的SegFaults下面的代码（在ret = s->iformat->read_packet(s, pkt)）。s-> iformat为零。
建议？
编辑II-对不起，获得后源代码****编辑iii-更新的示例代码以模拟阅读TS PKT队列
/*
* Test program for video decoder
*/
#include <stdio.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
extern "C" {
#ifdef __cplusplus
#define __STDC_CONSTANT_MACROS
#ifdef _STDINT_H
#undef _STDINT_H
#endif
#include <stdint.h>
#endif
}
extern "C" {
#include "libavcodec/avcodec.h"
#include "libavformat/avformat.h"
#include "libswscale/swscale.h"
#include "libavutil/imgutils.h"
#include "libavutil/opt.h"
}
class VideoDecoder
{
public:
VideoDecoder();
bool rcvTsPacket(AVPacket &inTsPacket);
private:
AVCodec *mpDecoder;
AVCodecContext *mpDecoderContext;
AVFrame *mpDecodedFrame;
AVFormatContext *mpFmtContext;
};
VideoDecoder::VideoDecoder()
{
av_register_all();
// FORMAT CONTEXT SETUP
mpFmtContext = avformat_alloc_context();
mpFmtContext->flags = AVFMT_NOFILE;
// ????? WHAT ELSE ???? //
// DECODER SETUP
mpDecoder = avcodec_find_decoder(AV_CODEC_ID_H264);
if (!mpDecoder)
{
printf("Could not load decodern");
exit(11);
}
mpDecoderContext = avcodec_alloc_context3(NULL);
if (avcodec_open2(mpDecoderContext, mpDecoder, NULL) < 0)
{
printf("Cannot open decoder contextn");
exit(1);
}
mpDecodedFrame = av_frame_alloc();
}
bool
VideoDecoder::rcvTsPacket(AVPacket &inTsPkt)
{
bool ret = true;
if ((av_read_frame(mpFmtContext, &inTsPkt)) < 0)
{
printf("Error in av_read_frame()n");
ret = false;
}
else
{
// success. Decode the TS packet
int got;
int len = avcodec_decode_video2(mpDecoderContext, mpDecodedFrame, &got, &inTsPkt);
if (len < 0)
ret = false;
if (got)
printf("GOT A DECODED FRAMEn");
}
return ret;
}
int
main(int argc, char **argv)
{
if (argc != 2)
{
printf("Usage: %s tsInFilen", argv[0]);
exit(1);
}
FILE *tsInFile = fopen(argv[1], "r");
if (!tsInFile)
{
perror("Could not open TS input file");
exit(2);
}
unsigned int tsPktNum = 0;
uint8_t tsBuffer[256];
AVPacket tsPkt;
av_init_packet(&tsPkt);
VideoDecoder vDecoder;
while (!feof(tsInFile))
{
tsPktNum++;
tsPkt.size = 188;
tsPkt.data = tsBuffer;
fread(tsPkt.data, 188, 1, tsInFile);
vDecoder.rcvTsPacket(tsPkt);
}
}
我有一些代码片段，可能会帮助您使用MPEG-TS。
从我的数据包线开始，该线程将每个数据包检查针对我已经找到的流ID，并获得了编解码器上下文：
void *FFMPEG::thread_packet_function(void *arg) {
FFMPEG *ffmpeg = (FFMPEG*)arg;
for (int c = 0; c < MAX_PACKETS; c++)
ffmpeg->free_packets[c] = &ffmpeg->packet_list[c];
ffmpeg->packet_pos = MAX_PACKETS;
Audio.start_decoding();
Video.start_decoding();
Subtitle.start_decoding();
while (!ffmpeg->thread_quit) {
if (ffmpeg->packet_pos != 0 &&
Audio.okay_add_packet() &&
Video.okay_add_packet() &&
Subtitle.okay_add_packet()) {
pthread_mutex_lock(&ffmpeg->packet_mutex); // get free packet
AVPacket *pkt = ffmpeg->free_packets[--ffmpeg->packet_pos]; // pre decrement
pthread_mutex_unlock(&ffmpeg->packet_mutex);
if ((av_read_frame(ffmpeg->fContext, pkt)) >= 0) { // success
int id = pkt->stream_index;
if (id == ffmpeg->aud_stream.stream_id) Audio.add_packet(pkt);
else if (id == ffmpeg->vid_stream.stream_id) Video.add_packet(pkt);
else if (id == ffmpeg->sub_stream.stream_id) Subtitle.add_packet(pkt);
else { // unknown packet
av_packet_unref(pkt);
pthread_mutex_lock(&ffmpeg->packet_mutex); // put packet back
ffmpeg->free_packets[ffmpeg->packet_pos++] = pkt;
pthread_mutex_unlock(&ffmpeg->packet_mutex);
//LOGI("Dumping unknown packet, id %d", id);
}
} else {
av_packet_unref(pkt);
pthread_mutex_lock(&ffmpeg->packet_mutex); // put packet back
ffmpeg->free_packets[ffmpeg->packet_pos++] = pkt;
pthread_mutex_unlock(&ffmpeg->packet_mutex);
//LOGI("No packet read");
}
} else { // buffers full so yield
//LOGI("Packet reader on hold: Audio-%d, Video-%d, Subtitle-%d",
// Audio.packet_pos, Video.packet_pos, Subtitle.packet_pos);
usleep(1000);
//sched_yield();
}
}
return 0;
}
每个用于音频，视频和字幕的解码器都有其自己的线程，这些线程从上面的线程中以戒指缓冲区接收数据包。我不得不将解码器分为自己的线程，因为当我开始使用Deinterlace Filter时，CPU的使用正在增加。
我的视频解码器会从缓冲区中读取数据包，并且完成数据包后，将其发送回去，可以再次使用。平衡数据包缓冲区一旦一切运行就不会花费太多时间。
这是我的视频解码器中的剪切：
void *VideoManager::decoder(void *arg) {
LOGI("Video decoder started");
VideoManager *mgr = (VideoManager *)arg;
while (!ffmpeg.thread_quit) {
pthread_mutex_lock(&mgr->packet_mutex);
if (mgr->packet_pos != 0) {
// fetch first packet to decode
AVPacket *pkt = mgr->packets[0];
// shift list down one
for (int c = 1; c < mgr->packet_pos; c++) {
mgr->packets[c-1] = mgr->packets[c];
}
mgr->packet_pos--;
pthread_mutex_unlock(&mgr->packet_mutex); // finished with packets array
int got;
AVFrame *frame = ffmpeg.vid_stream.frame;
avcodec_decode_video2(ffmpeg.vid_stream.context, frame, &got, pkt);
ffmpeg.finished_with_packet(pkt);
if (got) {
#ifdef INTERLACE_ALL
if (!frame->interlaced_frame) mgr->add_av_frame(frame, 0);
else {
if (!mgr->filter_initialised) mgr->init_filter_graph(frame);
av_buffersrc_add_frame_flags(mgr->filter_src_ctx, frame, AV_BUFFERSRC_FLAG_KEEP_REF);
int c = 0;
while (true) {
AVFrame *filter_frame = ffmpeg.vid_stream.filter_frame;
int result = av_buffersink_get_frame(mgr->filter_sink_ctx, filter_frame);
if (result == AVERROR(EAGAIN) ||
result == AVERROR(AVERROR_EOF) ||
result < 0)
break;
mgr->add_av_frame(filter_frame, c++);
av_frame_unref(filter_frame);
}
//LOGI("Interlaced %d frames, decode %d, playback %d", c, mgr->decode_pos, mgr->playback_pos);
}
#elif defined(INTERLACE_HALF)
if (!frame->interlaced_frame) mgr->add_av_frame(frame, 0);
else {
if (!mgr->filter_initialised) mgr->init_filter_graph(frame);
av_buffersrc_add_frame_flags(mgr->filter_src_ctx, frame, AV_BUFFERSRC_FLAG_KEEP_REF);
int c = 0;
while (true) {
AVFrame *filter_frame = ffmpeg.vid_stream.filter_frame;
int result = av_buffersink_get_frame(mgr->filter_sink_ctx, filter_frame);
if (result == AVERROR(EAGAIN) ||
result == AVERROR(AVERROR_EOF) ||
result < 0)
break;
mgr->add_av_frame(filter_frame, c++);
av_frame_unref(filter_frame);
}
//LOGI("Interlaced %d frames, decode %d, playback %d", c, mgr->decode_pos, mgr->playback_pos);
}
#else
mgr->add_av_frame(frame, 0);
#endif
}
//LOGI("decoded video packet");
} else {
pthread_mutex_unlock(&mgr->packet_mutex);
}
}
LOGI("Video decoder ended");
}
您可以看到，在来回传递数据包时，我正在使用Mutex。
获得了框架后，我只会从框架中复制YUV缓冲区，以便以后使用到另一个缓冲区列表中。我不转换Yuv，我使用的着色器将YUV转换为GPU上的RGB。
下一个片段将我的解码框架添加到我的缓冲区列表中。这可能有助于了解如何处理数据。
void VideoManager::add_av_frame(AVFrame *frame, int field_num) {
int y_linesize = frame->linesize[0];
int u_linesize = frame->linesize[1];
int hgt = frame->height;
int y_buffsize = y_linesize * hgt;
int u_buffsize = u_linesize * hgt / 2;
int buffsize = y_buffsize + u_buffsize + u_buffsize;
VideoBuffer *buffer = &buffers[decode_pos];
if (ffmpeg.is_network && playback_pos == decode_pos) { // patched 25/10/16 wlgfx
buffer->used = false;
if (!buffer->data) buffer->data = (char*)mem.alloc(buffsize);
if (!buffer->data) {
LOGI("Dropped frame, allocation error");
return;
}
} else if (playback_pos == decode_pos) {
LOGI("Dropped frame, ran out of decoder frame buffers");
return;
} else if (!buffer->data) {
buffer->data = (char*)mem.alloc(buffsize);
if (!buffer->data) {
LOGI("Dropped frame, allocation error.");
return;
}
}
buffer->y_frame = buffer->data;
buffer->u_frame = buffer->y_frame + y_buffsize;
buffer->v_frame = buffer->y_frame + y_buffsize + u_buffsize;
buffer->wid = frame->width;
buffer->hgt = hgt;
buffer->y_linesize = y_linesize;
buffer->u_linesize = u_linesize;
int64_t pts = av_frame_get_best_effort_timestamp(frame);
buffer->pts = pts;
buffer->buffer_size = buffsize;
double field_add = av_q2d(ffmpeg.vid_stream.context->time_base) * field_num;
buffer->frame_time = av_q2d(ts_stream) * pts + field_add;
memcpy(buffer->y_frame, frame->data[0], (size_t) (buffer->y_linesize * buffer->hgt));
memcpy(buffer->u_frame, frame->data[1], (size_t) (buffer->u_linesize * buffer->hgt / 2));
memcpy(buffer->v_frame, frame->data[2], (size_t) (buffer->u_linesize * buffer->hgt / 2));
buffer->used = true;
decode_pos = (++decode_pos) % MAX_VID_BUFFERS;
//if (field_num == 0) LOGI("Video %.2f, %d - %d",
// buffer->frame_time - Audio.pts_start_time, decode_pos, playback_pos);
}
如果还有其他我可能能帮助我的东西，请大声喊叫。： - ）
编辑：
摘要如何打开视频流上下文，该上下文自动确定编解码器，是H264，mpeg2还是另一个：
void FFMPEG::open_video_stream() {
vid_stream.stream_id = av_find_best_stream(fContext, AVMEDIA_TYPE_VIDEO,
-1, -1, &vid_stream.codec, 0);
if (vid_stream.stream_id == -1) return;
vid_stream.context = fContext->streams[vid_stream.stream_id]->codec;
if (!vid_stream.codec || avcodec_open2(vid_stream.context,
vid_stream.codec, NULL) < 0) {
vid_stream.stream_id = -1;
return;
}
vid_stream.frame = av_frame_alloc();
vid_stream.filter_frame = av_frame_alloc();
}
edit2：
这就是我打开输入流的方式，无论是文件还是URL。AvformatContext是流的主要上下文。
bool FFMPEG::start_stream(char *url_, float xtrim, float ytrim, int gain) {
aud_stream.stream_id = -1;
vid_stream.stream_id = -1;
sub_stream.stream_id = -1;
this->url = url_;
this->xtrim = xtrim;
this->ytrim = ytrim;
Audio.volume = gain;
Audio.init();
Video.init();
fContext = avformat_alloc_context();
if ((avformat_open_input(&fContext, url_, NULL, NULL)) != 0) {
stop_stream();
return false;
}
if ((avformat_find_stream_info(fContext, NULL)) < 0) {
stop_stream();
return false;
}
// network stream will overwrite packets if buffer is full
is_network = url.substr(0, 4) == "udp:" ||
url.substr(0, 4) == "rtp:" ||
url.substr(0, 5) == "rtsp:" ||
url.substr(0, 5) == "http:"; // added for wifi broadcasting ability
// determine if stream is audio only
is_mp3 = url.substr(url.size() - 4) == ".mp3";
LOGI("Stream: %s", url_);
if (!open_audio_stream()) {
stop_stream();
return false;
}
if (is_mp3) {
vid_stream.stream_id = -1;
sub_stream.stream_id = -1;
} else {
open_video_stream();
open_subtitle_stream();
if (vid_stream.stream_id == -1) { // switch to audio only
close_subtitle_stream();
is_mp3 = true;
}
}
LOGI("Audio: %d, Video: %d, Subtitle: %d",
aud_stream.stream_id,
vid_stream.stream_id,
sub_stream.stream_id);
if (aud_stream.stream_id != -1) {
LOGD("Audio stream time_base {%d, %d}",
aud_stream.context->time_base.num,
aud_stream.context->time_base.den);
}
if (vid_stream.stream_id != -1) {
LOGD("Video stream time_base {%d, %d}",
vid_stream.context->time_base.num,
vid_stream.context->time_base.den);
}
LOGI("Starting packet and decode threads");
thread_quit = false;
pthread_create(&thread_packet, NULL, &FFMPEG::thread_packet_function, this);
Display.set_overlay_timout(3.0);
return true;
}
edit ：（构造AVPacket）
构建一个avpacket发送到解码器...
AVPacket packet;
av_init_packet(&packet);
packet.data = myTSpacketdata; // pointer to the TS packet
packet.size = 188;
您应该能够重复使用数据包。它可能需要Unref'ing。
您必须首先使用avcodec库将压缩帧从文件中取出。然后，您可以使用AVCODEC_DECODE_VIDEO2解码它们。查看本教程http://dranger.com/ffmpeg/
