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Revolution of Open-source and film making towards open film making
6 octobre 2011, par
Mis à jour : Juillet 2013
Langue : English
Type : Texte
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Sur d’autres sites (10410)
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How to properly pass an asset FileDescriptor to FFmpeg using JNI in Android
6 janvier 2021, par William SeemannI'm trying to retrieve metadata in Android using FFmpeg, JNI and a Java FileDescriptor and it isn't' working. I know FFmpeg supports the pipe protocol so I'm trying to emmulate : "
cat test.mp3 | ffmpeg i pipe:0" programmatically. I use the following code to get a FileDescriptor from an asset bundled with the Android application :


FileDescriptor fd = getContext().getAssets().openFd("test.mp3").getFileDescriptor();
setDataSource(fd, 0, 0x7ffffffffffffffL); // native function, shown below



Then, in my native (In C++) code I get the FileDescriptor by calling :



static void wseemann_media_FFmpegMediaMetadataRetriever_setDataSource(JNIEnv *env, jobject thiz, jobject fileDescriptor, jlong offset, jlong length)
{
 //...

 int fd = jniGetFDFromFileDescriptor(env, fileDescriptor); // function contents show below

 //...
}

// function contents
static int jniGetFDFromFileDescriptor(JNIEnv * env, jobject fileDescriptor) {
 jint fd = -1;
 jclass fdClass = env->FindClass("java/io/FileDescriptor");

 if (fdClass != NULL) {
 jfieldID fdClassDescriptorFieldID = env->GetFieldID(fdClass, "descriptor", "I");
 if (fdClassDescriptorFieldID != NULL && fileDescriptor != NULL) {
 fd = env->GetIntField(fileDescriptor, fdClassDescriptorFieldID);
 }
 }

 return fd;
}



I then pass the file descriptor pipe # (In C) to FFmpeg :



char path[256] = "";

FILE *file = fdopen(fd, "rb");

if (file && (fseek(file, offset, SEEK_SET) == 0)) {
 char str[20];
 sprintf(str, "pipe:%d", fd);
 strcat(path, str);
}

State *state = av_mallocz(sizeof(State));
state->pFormatCtx = NULL;

if (avformat_open_input(&state->pFormatCtx, path, NULL, &options) != 0) { // Note: path is in the format "pipe:<the fd="fd">"
 printf("Metadata could not be retrieved\n");
 *ps = NULL;
 return FAILURE;
}

if (avformat_find_stream_info(state->pFormatCtx, NULL) < 0) {
 printf("Metadata could not be retrieved\n");
 avformat_close_input(&state->pFormatCtx);
 *ps = NULL;
 return FAILURE;
}

// Find the first audio and video stream
for (i = 0; i < state->pFormatCtx->nb_streams; i++) {
 if (state->pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO && video_index < 0) {
 video_index = i;
 }

 if (state->pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_AUDIO && audio_index < 0) {
 audio_index = i;
 }

 set_codec(state->pFormatCtx, i);
}

if (audio_index >= 0) {
 stream_component_open(state, audio_index);
}

if (video_index >= 0) {
 stream_component_open(state, video_index);
}

printf("Found metadata\n");
AVDictionaryEntry *tag = NULL;
while ((tag = av_dict_get(state->pFormatCtx->metadata, "", tag, AV_DICT_IGNORE_SUFFIX))) {
 printf("Key %s: \n", tag->key);
 printf("Value %s: \n", tag->value);
}

*ps = state;
return SUCCESS;
</the>


My issue is
avformat_open_inputdoesn't fail but it also doesn't let me retrieve any metadata or frames, The same code works if I use a regular file URI (e.g file ://sdcard/test.mp3) as the path. What am I doing wrong ? Thanks in advance.


Note : if you would like to look at all of the code I'm trying to solve the issue in order to provide this functionality for my library : FFmpegMediaMetadataRetriever.


-
How to properly pass an asset FileDescriptor to FFmpeg using JNI in Android
15 juillet 2014, par William SeemannI’m trying to retrieve metadata in Android using FFmpeg, JNI and a Java FileDescriptor and it isn’t’ working. I know FFmpeg supports the pipe protocol so I’m trying to emmulate : "
cat test.mp3 | ffmpeg i pipe:0" programmatically. I use the following code to get a FileDescriptor from an asset bundled with the Android application :FileDescriptor fd = getContext().getAssets().openFd("test.mp3").getFileDescriptor();
setDataSource(fd, 0, 0x7ffffffffffffffL); // native function, shown belowThen, in my native (In C++) code I get the FileDescriptor by calling :
static void wseemann_media_FFmpegMediaMetadataRetriever_setDataSource(JNIEnv *env, jobject thiz, jobject fileDescriptor, jlong offset, jlong length)
{
//...
int fd = jniGetFDFromFileDescriptor(env, fileDescriptor); // function contents show below
//...
}
// function contents
static int jniGetFDFromFileDescriptor(JNIEnv * env, jobject fileDescriptor) {
jint fd = -1;
jclass fdClass = env->FindClass("java/io/FileDescriptor");
if (fdClass != NULL) {
jfieldID fdClassDescriptorFieldID = env->GetFieldID(fdClass, "descriptor", "I");
if (fdClassDescriptorFieldID != NULL && fileDescriptor != NULL) {
fd = env->GetIntField(fileDescriptor, fdClassDescriptorFieldID);
}
}
return fd;
}I then pass the file descriptor pipe # (In C) to FFmpeg :
char path[256] = "";
FILE *file = fdopen(fd, "rb");
if (file && (fseek(file, offset, SEEK_SET) == 0)) {
char str[20];
sprintf(str, "pipe:%d", fd);
strcat(path, str);
}
State *state = av_mallocz(sizeof(State));
state->pFormatCtx = NULL;
if (avformat_open_input(&state->pFormatCtx, path, NULL, &options) != 0) { // Note: path is in the format "pipe:<the fd="fd">"
printf("Metadata could not be retrieved\n");
*ps = NULL;
return FAILURE;
}
if (avformat_find_stream_info(state->pFormatCtx, NULL) < 0) {
printf("Metadata could not be retrieved\n");
avformat_close_input(&state->pFormatCtx);
*ps = NULL;
return FAILURE;
}
// Find the first audio and video stream
for (i = 0; i < state->pFormatCtx->nb_streams; i++) {
if (state->pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO && video_index < 0) {
video_index = i;
}
if (state->pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_AUDIO && audio_index < 0) {
audio_index = i;
}
set_codec(state->pFormatCtx, i);
}
if (audio_index >= 0) {
stream_component_open(state, audio_index);
}
if (video_index >= 0) {
stream_component_open(state, video_index);
}
printf("Found metadata\n");
AVDictionaryEntry *tag = NULL;
while ((tag = av_dict_get(state->pFormatCtx->metadata, "", tag, AV_DICT_IGNORE_SUFFIX))) {
printf("Key %s: \n", tag->key);
printf("Value %s: \n", tag->value);
}
*ps = state;
return SUCCESS;
</the>My issue is
avformat_open_inputdoesn’t fail but it also doesn’t let me retrieve any metadata or frames, The same code works if I use a regular file URI (e.g file ://sdcard/test.mp3) as the path. What am I doing wrong ? Thanks in advance.Note : if you would like to look at all of the code I’m trying to solve the issue in order to provide this functionality for my library : FFmpegMediaMetadataRetriever.
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opusdsp : adjust and optimize C function to match assembly
15 août 2019, par Lynneopusdsp : adjust and optimize C function to match assembly
The C and asm versions behaved differently _outside_ of the codec.
The C version returned pre-multiplied 'state' for the next execution
to use right away, while the assembly version outputted non-multiplied
'state' for the next execution to multiply to save instructions.
Since the initial state when initialized or seeking is always 0,
and since C and asm versions were never mixed, there was no issue.However, comparing outputs directly in checkasm doesn't work without
dividing the initial state by CELT_EMPH_COEFF and multiplying the
returned state by CELT_EMPH_COEFF for the assembly function.Since its actually faster to do this in C as well, copy the behavior the
asm versions use. As a reminder, the initial state 0 is divided by
CELT_EMPH_COEFF on seek and init (just in case in the future this is
changed, its technically more correct to init with CELT_EMPH_COEFF than 0,
however when seeking this will result in more audiable pops, unlike with 0
where the output gets in sync over a few samples).
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