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Emballe Médias : Mettre en ligne simplement des documents
29 octobre 2010, parLe plugin emballe médias a été développé principalement pour la distribution mediaSPIP mais est également utilisé dans d’autres projets proches comme géodiversité par exemple. Plugins nécessaires et compatibles
Pour fonctionner ce plugin nécessite que d’autres plugins soient installés : CFG Saisies SPIP Bonux Diogène swfupload jqueryui
D’autres plugins peuvent être utilisés en complément afin d’améliorer ses capacités : Ancres douces Légendes photo_infos spipmotion (...) -
Personnaliser les catégories
21 juin 2013, parFormulaire de création d’une catégorie
Pour ceux qui connaissent bien SPIP, une catégorie peut être assimilée à une rubrique.
Dans le cas d’un document de type catégorie, les champs proposés par défaut sont : Texte
On peut modifier ce formulaire dans la partie :
Administration > Configuration des masques de formulaire.
Dans le cas d’un document de type média, les champs non affichés par défaut sont : Descriptif rapide
Par ailleurs, c’est dans cette partie configuration qu’on peut indiquer le (...) -
Publier sur MédiaSpip
13 juin 2013Puis-je poster des contenus à partir d’une tablette Ipad ?
Oui, si votre Médiaspip installé est à la version 0.2 ou supérieure. Contacter au besoin l’administrateur de votre MédiaSpip pour le savoir
Sur d’autres sites (6518)
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Android FFmpeg Video Player
11 mars 2013, par DilipI want to play video using
FFmpegfor this have used some code,But it open file but not drawing frames thowing Unhandled page fault exception.Java Code :
public class MainActivity extends Activity {
private static native void openFile();
private static native void drawFrame(Bitmap bitmap);
private static native void drawFrameAt(Bitmap bitmap, int secs);
private Bitmap mBitmap;
private int mSecs = 0;
static {
System.loadLibrary("ffmpegutils");
}
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// setContentView(new VideoView(this));
setContentView(R.layout.main);
mBitmap = Bitmap.createBitmap(320, 240, Bitmap.Config.ARGB_8888);
openFile();
Button btn = (Button) findViewById(R.id.frame_adv);
btn.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
try {
drawFrame(mBitmap);
ImageView i = (ImageView) findViewById(R.id.frame);
i.setImageBitmap(mBitmap);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}}Jni code :
#include
#include
#include
#include <android></android>log.h>
#include <android></android>bitmap.h>
#include <libavcodec></libavcodec>avcodec.h>
#include <libavformat></libavformat>avformat.h>
#include <libswscale></libswscale>swscale.h>
#define LOG_TAG "FFMPEGSample"
#define LOGI(...) __android_log_print(ANDROID_LOG_INFO,LOG_TAG,__VA_ARGS__)
#define LOGE(...) __android_log_print(ANDROID_LOG_ERROR,LOG_TAG,__VA_ARGS__)
/* Cheat to keep things simple and just use some globals. */
AVFormatContext *pFormatCtx;
AVCodecContext *pCodecCtx;
AVFrame *pFrame;
AVFrame *pFrameRGB;
int videoStream;
/*
* Write a frame worth of video (in pFrame) into the Android bitmap
* described by info using the raw pixel buffer. It's a very inefficient
* draw routine, but it's easy to read. Relies on the format of the
* bitmap being 8bits per color component plus an 8bit alpha channel.
*/
static void fill_bitmap(AndroidBitmapInfo* info, void *pixels, AVFrame *pFrame) {
uint8_t *frameLine;
int yy;
for (yy = 0; yy < info->height; yy++) {
uint8_t* line = (uint8_t*) pixels;
frameLine = (uint8_t *) pFrame->data[0] + (yy * pFrame->linesize[0]);
int xx;
for (xx = 0; xx < info->width; xx++) {
int out_offset = xx * 4;
int in_offset = xx * 3;
line[out_offset] = frameLine[in_offset];
line[out_offset + 1] = frameLine[in_offset + 1];
line[out_offset + 2] = frameLine[in_offset + 2];
line[out_offset + 3] = 0;
}
pixels = (char*) pixels + info->stride;
}
}
void Java_com_churnlabs_ffmpegsample_MainActivity_openFile(JNIEnv * env,
jobject this) {
int ret;
int err;
int i;
AVCodec *pCodec;
uint8_t *buffer;
int numBytes;
av_register_all();
LOGE("Registered formats***********************************");
err = av_open_input_file(&pFormatCtx, "file:///mnt/sdcard/android.3gp",
NULL, 0, NULL);
LOGE("Called open file***************************************************");
if (err != 0) {
LOGE(
"Couldn't open file****************************************************");
return;
}
LOGE(
"Opened file***********************************************************");
if (av_find_stream_info(pFormatCtx) < 0) {
LOGE(
"Unable to get stream info*****************************************");
return;
}
videoStream = -1;
for (i = 0; i < pFormatCtx->nb_streams; i++) {
if (pFormatCtx->streams[i]->codec->codec_type == CODEC_TYPE_VIDEO) {
videoStream = i;
break;
}
}
if (videoStream == -1) {
LOGE("Unable to find video stream");
return;
}
LOGI("Video stream is [%d]", videoStream);
pCodecCtx = pFormatCtx->streams[videoStream]->codec;
pCodec = avcodec_find_decoder(pCodecCtx->codec_id);
if (pCodec == NULL) {
LOGE("Unsupported codec**********************************************");
return;
}
if (avcodec_open(pCodecCtx, pCodec) < 0) {
LOGE("Unable to open codec***************************************");
return;
}
pFrame = avcodec_alloc_frame();
pFrameRGB = avcodec_alloc_frame();
LOGI("Video size is [%d x %d]", pCodecCtx->width, pCodecCtx->height);
numBytes = avpicture_get_size(PIX_FMT_RGB24, pCodecCtx->width,
pCodecCtx->height);
buffer = (uint8_t *) av_malloc(numBytes * sizeof(uint8_t));
avpicture_fill((AVPicture *) pFrameRGB, buffer, PIX_FMT_RGB24,
pCodecCtx->width, pCodecCtx->height);
}
void Java_com_churnlabs_ffmpegsample_MainActivity_drawFrame(JNIEnv * env,
jobject this, jstring bitmap) {
AndroidBitmapInfo info;
void* pixels;
int ret;
int err;
int i;
int frameFinished = 0;
AVPacket packet;
static struct SwsContext *img_convert_ctx;
int64_t seek_target;
if ((ret = AndroidBitmap_getInfo(env, bitmap, &info)) < 0) {
LOGE("AndroidBitmap_getInfo() failed ! error=%d", ret);
return;
}
LOGE(
"Checked on the bitmap*************************************************");
if ((ret = AndroidBitmap_lockPixels(env, bitmap, &pixels)) < 0) {
LOGE("AndroidBitmap_lockPixels() failed ! error=%d", ret);
}
LOGE(
"Grabbed the pixels*******************************************************");
i = 0;
while ((i == 0) && (av_read_frame(pFormatCtx, &packet) >= 0)) {
if (packet.stream_index == videoStream) {
avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished, &packet);
if (frameFinished) {
LOGE("packet pts %llu", packet.pts);
// This is much different than the tutorial, sws_scale
// replaces img_convert, but it's not a complete drop in.
// This version keeps the image the same size but swaps to
// RGB24 format, which works perfect for PPM output.
int target_width = 320;
int target_height = 240;
img_convert_ctx = sws_getContext(pCodecCtx->width,
pCodecCtx->height, pCodecCtx->pix_fmt, target_width,
target_height, PIX_FMT_RGB24, SWS_BICUBIC, NULL, NULL,
NULL);
if (img_convert_ctx == NULL) {
LOGE("could not initialize conversion context\n");
return;
}
sws_scale(img_convert_ctx,
(const uint8_t* const *) pFrame->data, pFrame->linesize,
0, pCodecCtx->height, pFrameRGB->data,
pFrameRGB->linesize);
// save_frame(pFrameRGB, target_width, target_height, i);
fill_bitmap(&info, pixels, pFrameRGB);
i = 1;
}
}
av_free_packet(&packet);
}
AndroidBitmap_unlockPixels(env, bitmap);
}
int seek_frame(int tsms) {
int64_t frame;
frame = av_rescale(tsms, pFormatCtx->streams[videoStream]->time_base.den,
pFormatCtx->streams[videoStream]->time_base.num);
frame /= 1000;
if (avformat_seek_file(pFormatCtx, videoStream, 0, frame, frame,
AVSEEK_FLAG_FRAME) < 0) {
return 0;
}
avcodec_flush_buffers(pCodecCtx);
return 1;
}Log Trace
0): <6>AUO_TOUCH: ts_irqHandler: before disable_irq()
D/PrintK ( 57): <6>AUO_TOUCH: ts_irqWorkHandler: P1(313,750),P2(0,0)
D/PrintK ( 0): <6>AUO_TOUCH: ts_irqHandler: before disable_irq()
D/PrintK ( 57): <6>AUO_TOUCH: ts_irqWorkHandler: P1(0,0),P2(0,0)
E/FFMPEGSample( 2882): Checked on the bitmap*************************************************
E/FFMPEGSample( 2882): Grabbed the pixels*******************************************************
E/FFMPEGSample( 2882): packet pts 0
F/PrintK ( 2882): <2>Exception!!! bs.ffmpegsample: unhandled page fault (11) at 0x0000000c, code 0x017
F/PrintK ( 2882): <2>Exception!!! bs.ffmpegsample: unhandled page fault (11) at 0x0000000c, code 0x017
I/DEBUG ( 86): *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
F/DEBUG ( 86): *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
I/DEBUG ( 86): Build fingerprint: 'dell/streak/streak/8x50:2.2.2/FRG83G/eng.cmbuild.20110317.163900:user/release-keys'
I/DEBUG ( 86): Exception!!! pid: 2882, tid: 2882 >>> com.churnlabs.ffmpegsample <<<
F/DEBUG ( 86): Exception!!! pid: 2882, tid: 2882 >>> com.churnlabs.ffmpegsample <<<
I/DEBUG ( 86): signal 11 (SIGSEGV), fault addr 0000000c
F/DEBUG ( 86): signal 11 (SIGSEGV), fault addr 0000000c
I/DEBUG ( 86): r0 00000070 r1 00000000 r2 0024fca8 r3 afd42328
F/DEBUG ( 86): r0 00000070 r1 00000000 r2 0024fca8 r3 afd42328
I/DEBUG ( 86): r4 00000000 r5 00000000 r6 0000062c r7 0000a000
F/DEBUG ( 86): r4 00000000 r5 00000000 r6 0000062c r7 0000a000
I/DEBUG ( 86): r8 be9794f0 r9 428ab9d8 10 00000003 fp be979830
F/DEBUG ( 86): r8 be9794f0 r9 428ab9d8 10 00000003 fp be979830
I/DEBUG ( 86): ip ffffff90 sp be979448 lr afd0c633 pc afd0c320 cpsr 80000030
F/DEBUG ( 86): ip ffffff90 sp be979448 lr afd0c633 pc afd0c320 cpsr 80000030
I/DEBUG ( 86): d0 6472656767756265 d1 0000000000000000
I/DEBUG ( 86): d2 0000000000000000 d3 0000000044480000
I/DEBUG ( 86): d4 8000000000000000 d5 000000003f800000
I/DEBUG ( 86): d6 0000000000000000 d7 4448000043f00000
I/DEBUG ( 86): d8 0000000000000000 d9 0000000000000000
I/DEBUG ( 86): d10 0000000000000000 d11 0000000000000000
I/DEBUG ( 86): d12 0000000000000000 d13 0000000000000000
I/DEBUG ( 86): d14 0000000000000000 d15 0000000000000000
I/DEBUG ( 86): d16 0000000000000000 d17 0000000000000000
I/DEBUG ( 86): d18 0000000000000000 d19 0000000000000000
I/DEBUG ( 86): d20 3ff0000000000000 d21 8000000000000000
I/DEBUG ( 86): d22 0000000000000000 d23 0000000500010004
I/DEBUG ( 86): d24 0101010101010101 d25 0000000000000000
I/DEBUG ( 86): d26 0000000000000000 d27 0000000000000000
I/DEBUG ( 86): d28 0000000000000000 d29 3ff0000000000000
I/DEBUG ( 86): d30 0000000000000000 d31 3ff0000000000000
I/DEBUG ( 86): scr 80000012
I/DEBUG ( 86):
I/DEBUG ( 86): #00 pc 0000c320 /system/lib/libc.so
F/DEBUG ( 86): #00 pc 0000c320 /system/lib/libc.so
I/DEBUG ( 86): #01 pc 0000c62e /system/lib/libc.so
F/DEBUG ( 86): #01 pc 0000c62e /system/lib/libc.so
I/DEBUG ( 86): #02 pc 0000cd3e /system/lib/libc.so
F/DEBUG ( 86): #02 pc 0000cd3e /system/lib/libc.so
I/DEBUG ( 86): #03 pc 0002d2c4 /system/lib/libskia.so
F/DEBUG ( 86): #03 pc 0002d2c4 /system/lib/libskia.so
I/DEBUG ( 86): #04 pc 000693ec /system/lib/libskia.so
F/DEBUG ( 86): #04 pc 000693ec /system/lib/libskia.so
I/DEBUG ( 86): #05 pc 00064d70 /system/lib/libskia.so
F/DEBUG ( 86): #05 pc 00064d70 /system/lib/libskia.so
I/DEBUG ( 86): #06 pc 0004dea8 /system/lib/libandroid_runtime.so
F/DEBUG ( 86): #06 pc 0004dea8 /system/lib/libandroid_runtime.so
I/DEBUG ( 86): #07 pc 00016df4 /system/lib/libdvm.so
F/DEBUG ( 86): #07 pc 00016df4 /system/lib/libdvm.so
I/DEBUG ( 86): #08 pc 00042904 /system/lib/libdvm.so
F/DEBUG ( 86): #08 pc 00042904 /system/lib/libdvm.so
I/DEBUG ( 86): #09 pc 0001bd58 /system/lib/libdvm.so
F/DEBUG ( 86): #09 pc 0001bd58 /system/lib/libdvm.so
I/DEBUG ( 86): #10 pc 00022550 /system/lib/libdvm.so
F/DEBUG ( 86): #10 pc 00022550 /system/lib/libdvm.so
I/DEBUG ( 86): #11 pc 000213f0 /system/lib/libdvm.so
F/DEBUG ( 86): #11 pc 000213f0 /system/lib/libdvm.so
I/DEBUG ( 86): #12 pc 00058c4a /system/lib/libdvm.so
F/DEBUG ( 86): #12 pc 00058c4a /system/lib/libdvm.so
I/DEBUG ( 86): #13 pc 00060e72 /system/lib/libdvm.so
F/DEBUG ( 86): #13 pc 00060e72 /system/lib/libdvm.so
I/DEBUG ( 86): #14 pc 0001bd58 /system/lib/libdvm.so
F/DEBUG ( 86): #14 pc 0001bd58 /system/lib/libdvm.so
I/DEBUG ( 86): #15 pc 00022550 /system/lib/libdvm.so
F/DEBUG ( 86): #15 pc 00022550 /system/lib/libdvm.so
I/DEBUG ( 86): #16 pc 000213f0 /system/lib/libdvm.so
F/DEBUG ( 86): #16 pc 000213f0 /system/lib/libdvm.so
I/DEBUG ( 86): #17 pc 00058a90 /system/lib/libdvm.so
F/DEBUG ( 86): #17 pc 00058a90 /system/lib/libdvm.so
I/DEBUG ( 86): #18 pc 0004525e /system/lib/libdvm.so
F/DEBUG ( 86): #18 pc 0004525e /system/lib/libdvm.so
I/DEBUG ( 86): #19 pc 0002e574 /system/lib/libandroid_runtime.so
F/DEBUG ( 86): #19 pc 0002e574 /system/lib/libandroid_runtime.so
I/DEBUG ( 86): #20 pc 0002f5f6 /system/lib/libandroid_runtime.so
F/DEBUG ( 86): #20 pc 0002f5f6 /system/lib/libandroid_runtime.so
I/DEBUG ( 86): #21 pc 00008ca8 /system/bin/app_process
F/DEBUG ( 86): #21 pc 00008ca8 /system/bin/app_process
I/DEBUG ( 86): #22 pc 0000d3d0 /system/lib/libc.so
F/DEBUG ( 86): #22 pc 0000d3d0 /system/lib/libc.so
I/DEBUG ( 86):
I/DEBUG ( 86): code around pc:
I/DEBUG ( 86): afd0c300 19d94f56 42ba690f 80a4f0c0 94001814
I/DEBUG ( 86): afd0c310 f08042a2 68d1809f 42916994 6895d00e
I/DEBUG ( 86): afd0c320 429668ee 8096f040 4296688e 8092f040
I/DEBUG ( 86): afd0c330 bf2442bd 608d60e9 e08bd21b b1116951
I/DEBUG ( 86): afd0c340 0514f102 6911e007 f102b191 e0020510
I/DEBUG ( 86):
I/DEBUG ( 86): code around lr:
I/DEBUG ( 86): afd0c610 60f11008 f8c1608e 4e31c00c f10319a1
I/DEBUG ( 86): afd0c620 608a0608 e04b614d b1b2684a f7ff4628
I/DEBUG ( 86): afd0c630 e00ffe23 0f41f115 f04fbf88 d80c35ff
I/DEBUG ( 86): afd0c640 350b4927 0507f025 68431860 4628b12b
I/DEBUG ( 86): afd0c650 fc1cf7ff 28004606 4e21d132 689119a2
I/DEBUG ( 86):
I/DEBUG ( 86): stack:
I/DEBUG ( 86): be979408 000001e0
I/DEBUG ( 86): be97940c be979494 [stack]
I/DEBUG ( 86): be979410 be979438 [stack]
I/DEBUG ( 86): be979414 be979478 [stack]
I/DEBUG ( 86): be979418 0012f484 [heap]
I/DEBUG ( 86): be97941c be979428 [stack]
I/DEBUG ( 86): be979420 00000000
I/DEBUG ( 86): be979424 ab163cec /system/lib/libskia.so
I/DEBUG ( 86): be979428 3f800000
I/DEBUG ( 86): be97942c 80000000 /system/lib/libicudata.so
I/DEBUG ( 86): be979430 00000000
I/DEBUG ( 86): be979434 80000000 /system/lib/libicudata.so
I/DEBUG ( 86): be979438 3f800000
I/DEBUG ( 86): be97943c 00000000
I/DEBUG ( 86): be979440 df002777
I/DEBUG ( 86): be979444 e3a070ad
I/DEBUG ( 86): #00 be979448 0024fd18 [heap]
I/DEBUG ( 86): be97944c afd4372c /system/lib/libc.so
I/DEBUG ( 86): be979450 000000c5
I/DEBUG ( 86): be979454 afd42328 /system/lib/libc.so
I/DEBUG ( 86): be979458 00000070
I/DEBUG ( 86): be97945c 0000062c
I/DEBUG ( 86): be979460 00000003
I/DEBUG ( 86): be979464 afd0c633 /system/lib/libc.so
I/DEBUG ( 86): #01 be979468 be9794c8 [stack]
I/DEBUG ( 86): be97946c 00000000
I/DEBUG ( 86): be979470 002576bc [heap]
I/DEBUG ( 86): be979474 ab163d2c /system/lib/libskia.so
I/DEBUG ( 86): be979478 00000000
I/DEBUG ( 86): be97947c 00000000
I/DEBUG ( 86): be979480 44480000 /system/framework/framework-res.apk
I/DEBUG ( 86): be979484 00000068
I/DEBUG ( 86): be979488 00000002
I/DEBUG ( 86): be97948c 00000068
I/DEBUG ( 86): be979490 00000003
I/DEBUG ( 86): be979494 afd0cd41 /system/lib/libc.so
E/Parcel ( 841): Reading a NULL string not supported here.Can any plz suggest me where I'm doing wrong.
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Grand Unified Theory of Compact Disc
1er février 2013, par Multimedia Mike — GeneralThis is something I started writing about a decade ago (and I almost certainly have some of it wrong), back when compact discs still had a fair amount of relevance. Back around 2002, after a few years investigating multimedia technology, I took an interest in compact discs of all sorts. Even though there may seem to be a wide range of CD types, I generally found that they’re all fundamentally the same. I thought I would finally publishing something, incomplete though it may be.
Physical Perspective
There are a lot of ways to look at a compact disc. First, there’s the physical format, where a laser detects where pits/grooves have disturbed the smooth surface (a.k.a. lands). A lot of technical descriptions claim that these lands and pits on a CD correspond to ones and zeros. That’s not actually true, but you have to decide what level of abstraction you care about, and that abstraction is good enough if you only care about the discs from a software perspective.Grand Unified Theory (Software Perspective)
Looking at a disc from a software perspective, I have generally found it useful to view a CD as a combination of a 2 main components :- table of contents (TOC)
- a long string of sectors, each of which is 2352 bytes long
I like to believe that’s pretty much all there is to it. All of the information on a CD is stored as a string of sectors that might be chopped up into a series of anywhere from 1-99 individual tracks. The exact sector locations where these individual tracks begin are defined in the TOC.
Audio CDs (CD-DA / Red Book)
The initial purpose for the compact disc was to store digital audio. The strange sector size of 2352 bytes is an artifact of this original charter. “CD quality audio”, as any multimedia nerd knows, is formally defined as stereo PCM samples that are each 16 bits wide and played at a frequency of 44100 Hz.
(44100 audio frames / 1 second) * (2 samples / audio frame) * (16 bits / 1 sample) * (1 byte / 8 bits) = 176,400 bytes / second (176,400 bytes / 1 second) / (2352 bytes / 1 sector) = 75
75 is the number of sectors required to store a single second of CD-quality audio. A single sector stores 1/75th of a second, or a ‘frame’ of audio (though I think ‘frame’ gets tossed around at all levels when describing CD formats).
The term “red book” is thrown around in relation to audio CDs. There is a series of rainbow books that define various optical disc standards and the red book describes audio CDs.
Basic Data CD-ROMs (Mode 1 / Yellow Book)
Somewhere along the line, someone decided that general digital information could be stored on these discs. Hence, the CD-ROM was born. The standard model above still applies– TOC and string of 2352-byte sectors. However, it’s generally only useful to have a single track on a CD-ROM. Thus, the TOC only lists a single track. That single track can easily span the entire disc (something that would be unusual for a typical audio CD).While the model is mostly the same, the most notable difference between and audio CD and a plain CD-ROM is that, while each sector is 2352 bytes long, only 2048 bytes are used to store actual data payload. The remaining bytes are used for synchronization and additional error detection/correction.
At least, the foregoing is true for mode 1 / form 1 CD-ROMs (which are the most common). “Mode 1″ CD-ROMs are defined by a publication called the yellow book. There is also mode 1 / form 2. This forgoes the additional error detection and correction afforded by form 1 and dedicates 2336 of the 2352 sector bytes to the data payload.
CD-ROM XA (Mode 2 / Green Book)
From a software perspective, these are similar to mode 1 CD-ROMs. There are also 2 forms here. The first form gives a 2048-byte data payload while the second form yields a 2324-byte data payload.Video CD (VCD / White Book)
These are CD-ROM XA discs that carry MPEG-1 video and audio data.Photo CD (Beige Book)
This is something I have never personally dealt with. But it’s supposed to conform to the CD-ROM XA standard and probably fits into my model. It seems to date back to early in the CD-ROM era when CDs were particularly cost prohibitive.Multisession CDs (Blue Book)
Okay, I admit that this confuses me a bit. Multisession discs allow a user to burn multiple sessions to a single recordable disc. I.e., burn a lump of data, then burn another lump at a later time, and the final result will look like all the lumps were recorded as the same big lump. I remember this being incredibly useful and cost effective back when recordable CDs cost around US$10 each (vs. being able to buy a spindle of 100 CD-Rs for US$10 or less now). Studying the cdrom.h file for the Linux OS, I found a system call named CDROMMULTISESSION that returns the sector address of the start of the last session. If I were to hypothesize about how to make this fit into my model, I might guess that the TOC has some hint that the disc was recorded in multisession (which needs to be decided up front) and the CDROMMULTISESSION call is made to find the last session. Or it could be that a disc read initialization operation always leads off with the CDROMMULTISESSION query in order to determine this.I suppose I could figure out how to create a multisession disc with modern software, or possibly dig up a multisession disc from 15+ years ago, and then figure out how it should be read.
CD-i
This type puzzles my as well. I do have some CD-i discs and I thought that I could read them just fine (the last time I looked, which was many years ago). But my research for this blog post has me thinking that I might not have been seeing the entire picture when I first studied my CD-i samples. I was able to see some of the data, but sources indicate that only proper CD-i hardware is able to see all of the data on the disc (apparently, the TOC doesn’t show all of the sectors on disc).Hybrid CDs (Data + Audio)
At some point, it became a notable selling point for an audio CD to have a data track with bonus features. Even more common (particularly in the early era of CD-ROMs) were computer and console games that used the first track of a disc for all the game code and assets and the remaining tracks for beautifully rendered game audio that could also be enjoyed outside the game. Same model : TOC points to the various tracks and also makes notes about which ones are data and which are audio.There seems to be 2 distinct things described above. One type is the mixed mode CD which generally has the data in the first track and the audio in tracks 2..n. Then there is the enhanced CD, which apparently used multisession recording and put the data at the end. I think that the reasoning for this is that most audio CD player hardware would only read tracks from the first session and would have no way to see the data track. This was a positive thing. By contrast, when placing a mixed-mode CD into an audio player, the data track would be rendered as nonsense noise.
Subchannels
There’s at least one small detail that my model ignores : subchannels. CDs can encode bits of data in subchannels in sectors. This is used for things like CD-Text and CD-G. I may need to revisit this.In Summary
There’s still a lot of ground to cover, like how those sectors might be formatted to show something useful (e.g., filesystems), and how the model applies to other types of optical discs. Sounds like something for another post. -
OpenGL + ffmpeg slow in fullscreen mode
28 mars 2013, par fushaI'm trying to play a video file using ffmpeg and OpenGL + SDL. The playback is very slow and flickering. The code is an accumulation from different blogs/sites and I'm not really very sure what is going on. Sorry to post such a long code but this is the minimized version. My actual code does not play well in windowed mode also. Somehow the version below plays smoothly in windowed mode.
#ifndef INT64_C
#define INT64_C(c) (int64_t)(c)
#define UINT64_C(c) (uint64_t)(c)
#endif
extern "C" {
#include <libavcodec></libavcodec>avcodec.h>
#include <libavformat></libavformat>avformat.h>
#include <libswscale></libswscale>swscale.h>
}
#include
#include <gl></gl>gl.h>
int fullscreen = 1, videoStream = -1, frameFinished=0;
const PixelFormat CONV_FORMAT = PIX_FMT_RGB24;
const char *fname = "moviesample.mp4";
AVFormatContext *pFormatCtx = NULL;
AVCodecContext *pCodecCtx = NULL;
AVCodec *pCodec = NULL;
AVFrame *pFrame = 0, *pFrameRGB = 0;
AVPacket packet;
AVDictionary *optionsDict = NULL;
struct SwsContext *sws_ctx = NULL;
GLuint texture_video;
void av_init();
void draw_frame();
int main(int argc, const char **argv) {
SDL_Event event;
av_init();
uint16_t width = fullscreen ? 1600 : pCodecCtx->width;
uint16_t height = fullscreen ? 900 : pCodecCtx->height;
SDL_Init(SDL_INIT_EVERYTHING);
SDL_GL_SetAttribute( SDL_GL_DOUBLEBUFFER, 1 );
SDL_SetVideoMode(width, height, 32,
SDL_OPENGL | SDL_HWPALETTE | SDL_HWSURFACE | SDL_HWACCEL |
(fullscreen ? SDL_FULLSCREEN : 0)
);
glEnable(GL_TEXTURE_2D);
glClearColor(0.0f, 0.4f, 0.4f, 0.0f);
glViewport(0, 0, width, height);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glMatrixMode( GL_MODELVIEW );
glLoadIdentity( );
glShadeModel( GL_SMOOTH );
glGenTextures(1, &texture_video);
glBindTexture(GL_TEXTURE_2D, texture_video);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, pCodecCtx->width, pCodecCtx->height,
0, GL_RGB, GL_UNSIGNED_BYTE, pFrameRGB->data[0]);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
sws_ctx = sws_getCachedContext(sws_ctx, pCodecCtx->width, pCodecCtx->height,
pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height, CONV_FORMAT,
SWS_BICUBIC, NULL, NULL, NULL);
while (1) {
draw_frame();
SDL_GL_SwapBuffers();
SDL_PollEvent(&event);
switch(event.type) {
case SDL_QUIT:
SDL_Quit();
exit(0);
break;
case SDL_KEYDOWN:
if (event.key.keysym.sym == SDLK_ESCAPE) {
SDL_Quit();
exit(0);
}
break;
default:
break;
}
}
return 0;
}
void draw_frame() {
if (av_read_frame(pFormatCtx, &packet)>=0) {
if(packet.stream_index==videoStream) {
avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished, &packet);
if(frameFinished) {
sws_scale (sws_ctx, (uint8_t const * const *)pFrame->data,
pFrame->linesize, 0, pCodecCtx->height, pFrameRGB->data,
pFrameRGB->linesize);
glBindTexture( GL_TEXTURE_2D, texture_video );
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, pCodecCtx->width,
pCodecCtx->height, GL_RGB, GL_UNSIGNED_BYTE, pFrameRGB->data[0]);
}
glClear(GL_COLOR_BUFFER_BIT);
glScalef(1.0f, -1.0f, 1.0f);
glBegin(GL_QUADS);
glTexCoord2f(0.0f, 0.0f);
glVertex3f(-1.0f, -1.0f, 0.0f);
glTexCoord2f(0.0f, 1.0f);
glVertex3f(-1.0f, 1.0f, 0.0f);
glTexCoord2f(1.0f, 1.0f);
glVertex3f(1.0f, 1.0f, 0.0f);
glTexCoord2f(1.0f, 0.0f);
glVertex3f(1.0f, -1.0f, 0.0f);
glEnd();
glScalef(1.0f, -1.0f, 1.0f);
}
av_free_packet(&packet);
} else {
av_seek_frame(pFormatCtx, videoStream, 0, AVSEEK_FLAG_FRAME);
}
}
void av_init() {
av_register_all();
avformat_open_input(&pFormatCtx, fname, NULL, NULL);
avformat_find_stream_info(pFormatCtx, NULL);
for(uint8_t i=0; inb_streams; i++)
if(pFormatCtx->streams[i]->codec->codec_type==AVMEDIA_TYPE_VIDEO) {
videoStream=i;
break;
}
pCodecCtx = pFormatCtx->streams[videoStream]->codec;
pCodec = avcodec_find_decoder(pCodecCtx->codec_id);
avcodec_open2(pCodecCtx, pCodec, &optionsDict);
pFrame = avcodec_alloc_frame();
pFrameRGB = avcodec_alloc_frame();
int bytes = avpicture_get_size(CONV_FORMAT, pCodecCtx->width,
pCodecCtx->height);
uint8_t *video_buffer = (uint8_t*)av_malloc( bytes * sizeof(uint8_t) );
avpicture_fill((AVPicture *)pFrameRGB, video_buffer, CONV_FORMAT,
pCodecCtx->width, pCodecCtx->height);
}
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