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La sauvegarde automatique de canaux SPIP
1er avril 2010, parDans le cadre de la mise en place d’une plateforme ouverte, il est important pour les hébergeurs de pouvoir disposer de sauvegardes assez régulières pour parer à tout problème éventuel.
Pour réaliser cette tâche on se base sur deux plugins SPIP : Saveauto qui permet une sauvegarde régulière de la base de donnée sous la forme d’un dump mysql (utilisable dans phpmyadmin) mes_fichiers_2 qui permet de réaliser une archive au format zip des données importantes du site (les documents, les éléments (...) -
Encodage et transformation en formats lisibles sur Internet
10 avril 2011MediaSPIP transforme et ré-encode les documents mis en ligne afin de les rendre lisibles sur Internet et automatiquement utilisables sans intervention du créateur de contenu.
Les vidéos sont automatiquement encodées dans les formats supportés par HTML5 : MP4, Ogv et WebM. La version "MP4" est également utilisée pour le lecteur flash de secours nécessaire aux anciens navigateurs.
Les documents audios sont également ré-encodés dans les deux formats utilisables par HTML5 :MP3 et Ogg. La version "MP3" (...) -
Contribute to documentation
13 avril 2011Documentation is vital to the development of improved technical capabilities.
MediaSPIP welcomes documentation by users as well as developers - including : critique of existing features and functions articles contributed by developers, administrators, content producers and editors screenshots to illustrate the above translations of existing documentation into other languages
To contribute, register to the project users’ mailing (...)
Sur d’autres sites (6516)
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FFMPEG Corrupt output remuxing MP4 (Using API in C) -First file OK, 2nd file onwards is not
25 janvier, par RichardPI have a simple application written in C - it takes the video from a RTSP camera and just writes to disk in 1 minute segments. The first file created works fine, plays on anlmost anything. The Second file does not play. Programatically, The trace shows they are the same code flows, but I cant seem to find where the problem is to allow the 2nd file to be play exactly the same as the first.


There are frames in the 2nd file but they are random. The second file is created EXACTLY the same way as the first.


Any help from a guru would be greatly appreciated.


EDIT : FIX - The output duration needs to be set before the trailer is written.


int actual_duration = (int)difftime(time(NULL), start_time);

for (int i = 0; i < output_ctx->nb_streams; i++) {
 output_ctx->streams[i]->duration = actual_duration * AV_TIME_BASE;
}

output_ctx->duration = actual_duration * AV_TIME_BASE;
printf("DURATION = %d\r\n",output_ctx->duration);

// Set the start_time for the output context
output_ctx->start_time = 0;

av_write_trailer(output_ctx);


Code flow


Open RTSP Stream 
A: Create File n context 
 Remux to file n 
 Wait for minute to change 
 Close File n context 
 increment n Goto A


Makefile


CC = gcc
CFLAGS = -Wall -g
LIBS = -lavformat -lavcodec -lavutil -lavdevice -lswscale -lavfilter -lavutil -lm -lz -lpthread

TARGET = rtsp_remux

all: $(TARGET)

$(TARGET): rtsp_remux.o
 $(CC) -o $(TARGET) rtsp_remux.o $(LIBS)

rtsp_remux.o: rtsp_remux.c
 $(CC) $(CFLAGS) -c rtsp_remux.c

clean:
 rm -f $(TARGET) rtsp_remux.o

.PHONY: all clean


rtsp_remux.c

#include <libavformat></libavformat>avformat.h>
#include <libavutil></libavutil>time.h>
#include 
#include 

#define OUTPUT_PREFIX "output"
#define OUTPUT_EXTENSION ".mp4"
#define MAX_FILES 4

int main(int argc, char *argv[]) {
 if (argc < 2) {
 fprintf(stderr, "Usage: %s <rtsp url="url">\n", argv[0]);
 return -1;
 }

 const char *rtsp_url = argv[1];
 AVFormatContext *input_ctx = NULL, *output_ctx = NULL;
 AVOutputFormat *output_fmt = NULL;
 AVPacket pkt;
 int ret, file_count = 0;
 char output_filename[1024];
 time_t current_time;
 struct tm *timeinfo;
 int rename_lock = 0;

 avformat_network_init();

 if ((ret = avformat_open_input(&input_ctx, rtsp_url, NULL, NULL)) < 0) {
 fprintf(stderr, "Could not open input file '%s'\n", rtsp_url);
 return -1;
 }

 if ((ret = avformat_find_stream_info(input_ctx, NULL)) < 0) {
 fprintf(stderr, "Failed to retrieve input stream information\n");
 return -1;
 }

 av_dump_format(input_ctx, 0, rtsp_url, 0);

 while (file_count < MAX_FILES) {
 snprintf(output_filename, sizeof(output_filename), "%s_%03d%s", OUTPUT_PREFIX, file_count, OUTPUT_EXTENSION);

 if ((ret = avformat_alloc_output_context2(&output_ctx, NULL, NULL, output_filename)) < 0) {
 fprintf(stderr, "Could not create output context\n");
 return -1;
 }

 output_fmt = output_ctx->oformat;

 for (int i = 0; i < input_ctx->nb_streams; i++) {
 AVStream *in_stream = input_ctx->streams[i];
 AVStream *out_stream = avformat_new_stream(output_ctx, NULL);
 if (!out_stream) {
 fprintf(stderr, "Failed allocating output stream\n");
 return -1;
 }

 if ((ret = avcodec_parameters_copy(out_stream->codecpar, in_stream->codecpar)) < 0) {
 fprintf(stderr, "Failed to copy codec parameters\n");
 return -1;
 }
 out_stream->codecpar->codec_tag = 0;
 }

 if (!(output_fmt->flags & AVFMT_NOFILE)) {
 if ((ret = avio_open(&output_ctx->pb, output_filename, AVIO_FLAG_WRITE)) < 0) {
 fprintf(stderr, "Could not open output file '%s'\n", output_filename);
 return -1;
 }
 }

 if ((ret = avformat_write_header(output_ctx, NULL)) < 0) {
 fprintf(stderr, "Error occurred when opening output file\n");
 return -1;
 }

 while (1) {
 current_time = time(NULL);
 timeinfo = localtime(&current_time);

 if (timeinfo->tm_sec == 0 && !rename_lock) {
 rename_lock = 1;
 break;
 } else if (timeinfo->tm_sec != 0) {
 rename_lock = 0;
 }

 if ((ret = av_read_frame(input_ctx, &pkt)) < 0)
 break;

 AVStream *in_stream = input_ctx->streams[pkt.stream_index];
 AVStream *out_stream = output_ctx->streams[pkt.stream_index];

 pkt.pts = av_rescale_q_rnd(pkt.pts, in_stream->time_base, out_stream->time_base, AV_ROUND_NEAR_INF | AV_ROUND_PASS_MINMAX);
 pkt.dts = av_rescale_q_rnd(pkt.dts, in_stream->time_base, out_stream->time_base, AV_ROUND_NEAR_INF | AV_ROUND_PASS_MINMAX);
 pkt.duration = av_rescale_q(pkt.duration, in_stream->time_base, out_stream->time_base);
 pkt.pos = -1;

 if ((ret = av_interleaved_write_frame(output_ctx, &pkt)) < 0) {
 fprintf(stderr, "Error muxing packet\n");
 break;
 }

 av_packet_unref(&pkt);
 }

 av_write_trailer(output_ctx);

 if (!(output_fmt->flags & AVFMT_NOFILE))
 avio_closep(&output_ctx->pb);

 avformat_free_context(output_ctx);

 file_count++;
 }

 avformat_close_input(&input_ctx);
 avformat_network_deinit();

 return 0;
}
</rtsp>

I have tried changing to pointers, freeing and different things. I was expecting the 2nd file created to behave identically to the first.


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Channel mapping in FFmpeg conversion of Dolby 7.1 mlp file to 8 channel wav file [closed]
21 avril 2024, par Stan DuncanI have a file with 7.1 audio with the following channel mapping (viewed using MediaInfo) :
L R C LFE Ls Rs Lb Rb

I want to convert it to an 8 channel riff64 wave file, so I'm using the following command :


ffmpeg.exe -i "input.mlp" -rf64 auto -c:a pcm_f32le "output.wav"

When I do this, the channel mapping in output.wav changes to (viewed using MediaInfo) :
L R C LFE Lb Rb Ls Rs

I'm not sure if this is just a label that gets slapped on there, or if it actually changes the channel positions (i.e., rear surround come out of side surround speakers and vice versa).


Is there a better command I should be using to ensure that the channel mapping is not altered ?


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FFMPEG- Duration of audio file is inaccurate
17 septembre 2015, par Tony ThanI have video file (mp4). I want to detach audio stream (AAC format) from that file and save in PC.
With below code, Generated aac file canplay now on KM player, but can not play on VLC player. Information of duration displays on player is wrong.
Please help me with this problem.err = avformat_open_input(input_format_context, filename, NULL, NULL);
if (err < 0) {
return err;
}
/* If not enough info to get the stream parameters, we decode the
first frames to get it. (used in mpeg case for example) */
ret = avformat_find_stream_info(*input_format_context, 0);
if (ret < 0) {
av_log(NULL, AV_LOG_FATAL, "%s: could not find codec parameters\n", filename);
return ret;
}
/* dump the file content */
av_dump_format(*input_format_context, 0, filename, 0);
for (size_t i = 0; i < (*input_format_context)->nb_streams; i++) {
AVStream *st = (*input_format_context)->streams[i];
if (st->codec->codec_type == AVMEDIA_TYPE_AUDIO) {
*input_codec_context = st->codec;
*input_audio_stream = st;
FILE *file = NULL;
file = fopen("C:\\Users\\MyPC\\Downloads\\Test.aac", "wb");
AVPacket reading_packet;
av_init_packet(&reading_packet);
while (av_read_frame(*input_format_context, &reading_packet) == 0) {
if (reading_packet.stream_index == (int) i) {
uint8_t adts_header[7];
unsigned int obj_type = 0;
unsigned int num_data_block = (reading_packet.size)/1024;
int rate_idx = st->codec->sample_rate, channels = st->codec->channels;
uint16_t frame_length;
// include the header length also
frame_length = reading_packet.size + 7;
/* We want the same metadata */
/* Generate ADTS header */
if(adts_header == NULL) return -1;
/* Sync point over a full byte */
adts_header[0] = 0xFF;
/* Sync point continued over first 4 bits + static 4 bits
* (ID, layer, protection)*/
adts_header[1] = 0xF1;
/* Object type over first 2 bits */
adts_header[2] = obj_type << 6;
/* rate index over next 4 bits */
adts_header[2] |= (rate_idx << 2);
/* channels over last 2 bits */
adts_header[2] |= (channels & 0x4) >> 2;
/* channels continued over next 2 bits + 4 bits at zero */
adts_header[3] = (channels & 0x3) << 6;
/* frame size over last 2 bits */
adts_header[3] |= (frame_length & 0x1800) >> 11;
/* frame size continued over full byte */
adts_header[4] = (frame_length & 0x1FF8) >> 3;
/* frame size continued first 3 bits */
adts_header[5] = (frame_length & 0x7) << 5;
/* buffer fullness (0x7FF for VBR) over 5 last bits*/
adts_header[5] |= 0x1F;
/* buffer fullness (0x7FF for VBR) continued over 6 first bits + 2 zeros
* number of raw data blocks */
adts_header[6] = 0xFA;
adts_header[6] |= num_data_block & 0x03; // Set raw Data blocks.
fwrite(adts_header, 1, 7, file);
fwrite(reading_packet.data, 1, reading_packet.size, file);
}
av_free_packet(&reading_packet);
}
fclose(file);
return 0;
}
}
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