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La conservation du net art au musée. Les stratégies à l’œuvre
26 mai 2011
Mis à jour : Juillet 2013
Langue : français
Type : Texte
Autres articles (101)
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Gestion générale des documents
13 mai 2011, parMédiaSPIP ne modifie jamais le document original mis en ligne.
Pour chaque document mis en ligne il effectue deux opérations successives : la création d’une version supplémentaire qui peut être facilement consultée en ligne tout en laissant l’original téléchargeable dans le cas où le document original ne peut être lu dans un navigateur Internet ; la récupération des métadonnées du document original pour illustrer textuellement le fichier ;
Les tableaux ci-dessous expliquent ce que peut faire MédiaSPIP (...) -
Le profil des utilisateurs
12 avril 2011, parChaque utilisateur dispose d’une page de profil lui permettant de modifier ses informations personnelle. Dans le menu de haut de page par défaut, un élément de menu est automatiquement créé à l’initialisation de MediaSPIP, visible uniquement si le visiteur est identifié sur le site.
L’utilisateur a accès à la modification de profil depuis sa page auteur, un lien dans la navigation "Modifier votre profil" est (...) -
Des sites réalisés avec MediaSPIP
2 mai 2011, parCette page présente quelques-uns des sites fonctionnant sous MediaSPIP.
Vous pouvez bien entendu ajouter le votre grâce au formulaire en bas de page.
Sur d’autres sites (13561)
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Intsallation of ffmpeg-php on Amazon Ec2 Linux AMI
1er décembre 2015, par TannyI am about two days into attempting to install FFMPEG-php with dependencies on an AWS EC2 instance running the Amazon Linux AMI. I’ve installed FFMPEG, and have read reportedly successful instructions on installing on Red Hat/Fedora. I have followed a number of tutorials and forum articles to do so, but have had no luck yet. As far as I can tell, the main problems are as followed :
I have installed all the dependency for ffmpeg-php. I run the following command successfully.
$wget http://downloads.sourceforge.net/project/ffmpeg-php/ffmpeg-php/0.6.0/ffmpeg-php-0.6.0.tbz2
$tar xvfj ffmpeg-php-0.6.0.tbz2
$phpizeBut when I run the following command it throw the error like below :
$sudo ./configure
configure : error : ffmpeg shared libraries not found. Make sure ffmpeg is compiled as shared libraries using the —enable-shared option}
I have used enable shared option with shared enable option but it throw the same error.
On to my question : Has anyone successfully installed FFMPEG-php on Amazon Linux ? Is there a fundamental incompatibility ? If anyone could share specific instructions on installing ffmpeg-php on amazon linux I would be greatly appreciative. Any other insights/experiences would also be appreciated.
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ffmpeg c++/cli wrapper for using in c# . AccessViolationException after call dll function by it's pointer
25 juillet 2015, par skynet_vMy target is to write a c++/cli wrap arount ffmpeg library, using by importing ffmpeg functions from dll-modules.
Later I will use this interface in c#.
This is my challenge, don’t ask me why))So i’ve implemented Wrap class, which is listed below :
namespace FFMpegWrapLib
{
public class Wrap
{
private:
public:
//wstring libavcodecDllName = "avcodec-56.dll";
//wstring libavformatDllName = "avformat-56.dll";
//wstring libswscaleDllName = "swscale-3.dll";
//wstring libavutilDllName = "avutil-54.dll";
HMODULE libavcodecDLL;
HMODULE libavformatDLL;
HMODULE libswsscaleDLL;
HMODULE libavutilDLL;
AVFormatContext **pFormatCtx = nullptr;
AVCodecContext *pCodecCtxOrig = nullptr;
AVCodecContext *pCodecCtx = nullptr;
AVCodec **pCodec = nullptr;
AVFrame **pFrame = nullptr;
AVFrame **pFrameRGB = nullptr;
AVPacket *packet = nullptr;
int *frameFinished;
int numBytes;
uint8_t *buffer = nullptr;
struct SwsContext *sws_ctx = nullptr;
void Init();
void AVRegisterAll();
void Release();
bool SaveFrame(const char *pFileName, AVFrame * frame, int w, int h);
bool GetStreamInfo();
int FindVideoStream();
bool OpenInput(const char* file);
AVCodec* FindDecoder();
AVCodecContext* AllocContext3();
bool CopyContext();
bool OpenCodec2();
AVFrame* AllocFrame();
int PictureGetSize();
void* Alloc(size_t size);
int PictureFill(AVPicture *, const uint8_t *, enum AVPixelFormat, int, int);
SwsContext* GetSwsContext(int, int, enum AVPixelFormat, int, int, enum AVPixelFormat, int, SwsFilter *, SwsFilter *, const double *);
int ReadFrame(AVFormatContext *s, AVPacket *pkt);
int DecodeVideo2(AVCodecContext *avctx, AVFrame *picture, int *got_picture_ptr, const AVPacket *avpkt);
int SwsScale(struct SwsContext *c, const uint8_t *const srcSlice[], const int srcStride[], int srcSliceY, int srcSliceH, uint8_t *const dst[], const int dstStride[]);
void PacketFree(AVPacket *pkt);
void BufferFree(void *ptr);
void FrameFree(AVFrame **frame);
int CodecClose(AVCodecContext *);
void CloseInput(AVFormatContext **);
bool SeekFrame(AVFormatContext *s, int stream_index, int64_t timestamp, int flags);
Wrap();
~Wrap();
bool GetVideoFrame(char* str_in_file, char* str_out_img, uint64_t time);
};
public ref class managedWrap
{
public:
managedWrap(){}
~managedWrap(){ delete unmanagedWrap; }
bool GetVideoFrameToFile(char* str_in_file, char* str_out_img, uint64_t time)
{
return unmanagedWrap->GetVideoFrame(str_in_file, str_out_img, time);
}
static Wrap* unmanagedWrap = new Wrap();
};
}So the imports to libavcodec and etc. are succesful.
The problem is in AccessViolationException during calling dll func, for example, in OpenInput (i.e. av_open_input in native ffmpeg library)The OpenInput func code is below :
bool FFMpegWrapLib::Wrap::OpenInput(const char* file)
{
typedef int avformat_open_input(AVFormatContext **, const char *, AVInputFormat *, AVDictionary **);
avformat_open_input* pavformat_open_input = (avformat_open_input *)GetProcAddress(libavformatDLL, "avformat_open_input");
if (pavformat_open_input == nullptr)
{
throw exception("Unable to find avformat_open_input function address in libavformat module");
return false;
}
//pin_ptr<avformatcontext> pinFormatContext = &(new interior_ptr<avformatcontext>(pCodecCtx));
pFormatCtx = new AVFormatContext*;
//*pFormatCtx = new AVFormatContext;
int ret = pavformat_open_input(pFormatCtx, file, NULL, NULL); // here it fails
return ret == 0;
}
</avformatcontext></avformatcontext>So the problem, i think, is that class-fields of Wrap class are in secure memory. And ffmpeg works with native memory, initialising pFormatCtx variable by it’s address.
Can I avoid this, or it is impossible ? -
Mix video and audio to mp4 file with ffmpeg but audio does't keep step with video when playback
28 juillet 2015, par dragonflyI managed to write a program to record video(
h264
/aac
) on android with ffmpeg. The detail is as follows :-
Implement
android.hardware.Camera.PreviewCallback
to capture every frame from camera (yuv image
) and send it to the ffmpeg in the jni layer.@Override
public void onPreviewFrame(byte[] data, Camera camera) {
// Log.d(TAG, "onPreviewFrame");
if (mIsRecording) {
// Log.d(TAG, "handlePreviewFrame");
Parameters param = camera.getParameters();
Size s = param.getPreviewSize();
handlePreviewFrame(data, s.width, s.height, mBufSize);
}
camera.addCallbackBuffer(mPreviewBuffer);
}
private void handlePreviewFrame(byte[] data, int width, int height, int size) {
if (mFormats == ImageFormat.NV21) {
//process the yuv data
}
synchronized (mMuxer) {
//jni api
mMuxer.putAudioVisualData(mYuvData, size, 0);
}
} -
Use
android.media.AudioRecord
to read the pcm data from the microphone, write pcm data to ffmpeg in the jni layer in a loop.while (this.isRecording) {
int ret = audioRecord.read(tempBuffer, 0, 1024);
if (ret == AudioRecord.ERROR_INVALID_OPERATION) {
throw new IllegalStateException(
"read() returned AudioRecord.ERROR_INVALID_OPERATION");
} else if (ret == AudioRecord.ERROR_BAD_VALUE) {
throw new IllegalStateException("read() returned AudioRecord.ERROR_BAD_VALUE");
} else if (ret == AudioRecord.ERROR_INVALID_OPERATION) {
throw new IllegalStateException(
"read() returned AudioRecord.ERROR_INVALID_OPERATION");
}
// 处理数据
handleAudioData(tempBuffer, ret);
}
private void handleAudioData(short[] data, int size)
{
// convert to byte[]
//Log.d("VideoCaptureActivity", "handleAudioData");
ByteBuffer buffer = ByteBuffer.allocate(data.length * 2);
buffer.order(ByteOrder.LITTLE_ENDIAN);
buffer.asShortBuffer().put(data);
buffer.limit(size * 2);
byte[] bytes = buffer.array();
synchronized (muxing) {
Log.d(TAG, "putAudio Data :" + size*2);
muxing.putAudioVisualData(bytes, size * 2, 1);
}
} -
mix audio and video data in the jni layer. I refer to the example : https://ffmpeg.org/doxygen/trunk/muxing_8c-source.html
The problem is that the example demonstrates audio and video encoding from some dummy source data generated on the fly. I need to encode audio from microphone and video from camera.
I think the reason of my failure is that the pts in the expample is not applicable for my situation. my av function code is as follows :
static int write_video_frame(AVFormatContext *oc, OutputStream *ost, char *data,
int size) {
int ret;
AVCodecContext *c;
int got_packet = 0;
c = ost->st->codec;
AVPacket pkt = { 0 };
av_init_packet(&pkt);
if (!video_st.hwcodec) {
if (ost->zoom) {
zoom(oc, ost, data);
} else {
avpicture_fill((AVPicture*) ost->frame, (const uint8_t *) data,
c->pix_fmt, c->width, c->height);
}
av_frame_make_writable(ost->frame);
//ost->frame->pts = ost->next_pts++;
ost->frame->pts = frame_count;
/* encode the image */
//ALOGI("avcodec_encode_video2 start");
ret = avcodec_encode_video2(c, &pkt, ost->frame, &got_packet);
//ALOGI("avcodec_encode_video2 end");
if (ret < 0) {
ALOGE("Error encoding video frame: %s", av_err2str(ret));
return -1;
}
} else {
if (size != 0) {
pkt.data = (uint8_t *) data;
pkt.size = size;
pkt.pts = pkt.dts = ost->next_pts++;
got_packet = 1;
}
}
if (got_packet) {
//ALOGI("video write_frame start");
//pkt.pts = (int) timestamp;
ret = write_frame(oc, &c->time_base, ost->st, &pkt);
//ALOGI("video write_frame end");
if (ret < 0) {
ALOGE("Error while writing video frame: %s", av_err2str(ret));
return -1;
}
}
frame_count++;
return 0;
}
static int write_audio_frame(AVFormatContext *oc, OutputStream *ost, char *data) {
AVCodecContext *c;
AVPacket pkt = { 0 }; // data and size must be 0;
AVFrame *frame;
int ret;
int got_packet;
int dst_nb_samples;
av_init_packet(&pkt);
c = ost->st->codec;
if (audio_st.speex_echo_cancellation == 1
&& g_audio_echo_play_queue->start_flag == 1) {
//ALOGI("encode_audio_handler in echo_cancel");
QUEUE_ITEM* item = Get_Queue_Item(g_audio_echo_play_queue);
if (item) {
speex_dsp_echo_play_back((spx_int16_t *) item->data);
//ALOGI("encode_audio_handler echo_play begin speex_echo_play_back");
short *echo_processed = (short *) av_malloc(160 * sizeof(short));
speex_dsp_echo_capture((spx_int16_t *) data, echo_processed);
memcpy(data, (uint8_t *) echo_processed, 160);
av_free(echo_processed);
Free_Queue_Item(item, 1);
}
}
frame = ost->tmp_frame;
//update pts
//frame->pts = ost->next_pts;
//ost->next_pts += frame->nb_samples;
if (frame) {
/* convert samples from native format to destination codec format, using the resampler */
/* compute destination number of samples */
dst_nb_samples = av_rescale_rnd(
swr_get_delay(ost->swr_ctx, c->sample_rate) + frame->nb_samples,
c->sample_rate, c->sample_rate, AV_ROUND_UP);
memcpy(frame->data[0], data, frame->nb_samples * 2);
//frame->data[0] = data;
/* when we pass a frame to the encoder, it may keep a reference to it
* internally;
* make sure we do not overwrite it here
*/
ret = av_frame_make_writable(ost->frame);
if (ret < 0) {
ALOGE("write_audio_frame av_frame_make_writable ERROR %s",
av_err2str(ret));
return -1;
}
/* convert to destination format */
ret = swr_convert(ost->swr_ctx, ost->frame->data, dst_nb_samples,
(const uint8_t **) frame->data, frame->nb_samples);
if (ret < 0) {
ALOGI("Error while converting %s", av_err2str(ret));
return -1;
}
frame = ost->frame;
frame->pts = av_rescale_q(ost->samples_count,
(AVRational ) { 1, c->sample_rate }, c->time_base);
ost->samples_count += dst_nb_samples;
}
ret = avcodec_encode_audio2(c, &pkt, frame, &got_packet);
if (ret < 0) {
ALOGE("Error encoding audio frame: %s", av_err2str(ret));
return -1;
}
if (got_packet) {
//pkt.pts = (int) timestamp;
ret = write_frame(oc, &c->time_base, ost->st, &pkt);
if (ret < 0) {
ALOGE("Error while writing audio frame: %s", av_err2str(ret));
return -1;
}
}
return (frame || got_packet) ? 0 : 1;
}How do I deal with the pts of video and audio stream for my situation ? Who can give me some advice ?
Can I ignore the pts provided by ffmpeg and calculate the pts in the java layer by myself and transmit it to ffmpeg ?
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