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Keeping control of your media in your hands
13 avril 2011, parThe vocabulary used on this site and around MediaSPIP in general, aims to avoid reference to Web 2.0 and the companies that profit from media-sharing.
While using MediaSPIP, you are invited to avoid using words like "Brand", "Cloud" and "Market".
MediaSPIP is designed to facilitate the sharing of creative media online, while allowing authors to retain complete control of their work.
MediaSPIP aims to be accessible to as many people as possible and development is based on expanding the (...) -
Support de tous types de médias
10 avril 2011Contrairement à beaucoup de logiciels et autres plate-formes modernes de partage de documents, MediaSPIP a l’ambition de gérer un maximum de formats de documents différents qu’ils soient de type : images (png, gif, jpg, bmp et autres...) ; audio (MP3, Ogg, Wav et autres...) ; vidéo (Avi, MP4, Ogv, mpg, mov, wmv et autres...) ; contenu textuel, code ou autres (open office, microsoft office (tableur, présentation), web (html, css), LaTeX, Google Earth) (...)
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Ecrire une actualité
21 juin 2013, parPrésentez les changements dans votre MédiaSPIP ou les actualités de vos projets sur votre MédiaSPIP grâce à la rubrique actualités.
Dans le thème par défaut spipeo de MédiaSPIP, les actualités sont affichées en bas de la page principale sous les éditoriaux.
Vous pouvez personnaliser le formulaire de création d’une actualité.
Formulaire de création d’une actualité Dans le cas d’un document de type actualité, les champs proposés par défaut sont : Date de publication ( personnaliser la date de publication ) (...)
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How do you properly free a BitStreamFilter (bsf) without getting a double free error ?
19 janvier 2021, par Alexis WilkeI'm trying to write a C++ class handling MP4 movies via ffmpeg.


First I created a couple of functions to use with
std::unique<>()so that way things get released even on exceptions.

However, I get a double free when I try to free the BitStreamFilter object, yet the documentation clearly says that each
av_bsf_alloc()must be paired with anav_bsf_free()call.



@param ctxa pointer into which the pointer to the newly-allocated context
will be written. It must be freed withav_bsf_free()after the
filtering is done.



Note : emphasis mine.


However, at the time I call the
avformat_close_input()I get a double free error, even if I haven't used the two contexts for anything !? I'm thinking that there may be a packet that both allocate and both try to free. But since these two contexts are not directly connected, I really don't understand how they end up freeing something twice.

Below is code which reproduce the error (at least on an amd64 platform). Once compiled, you can just execute it. Make sure to specify a filename as in :


./ffmpeg_demuxer_test mymovie.mp4


I used the following command to compile & link the code :


$ /usr/bin/c++ -std=c++17 -DDEBUG -D_DEBUG -D_GLIBCXX_ASSERTIONS -g -O0 \
 -fsanitize=address -fsanitize=enum -fsanitize=unreachable \
 -o ffmpeg_demuxer_test ffmpeg_demuxer_test.cpp \
 -lavformat -lavcodec


Notice the
-fsanitize=...options to capture errors such as a double free error.

Here is the code :


extern "C" {
#include <libavformat></libavformat>avformat.h>
#include <libavformat></libavformat>avio.h>
#include <libavcodec></libavcodec>avcodec.h>
}
#include <iostream>
#include <memory>


void ffmpeg_demuxer_avformat_context_free(AVFormatContext * context)
{
 if(context != nullptr) avformat_close_input(&context);
}

void ffmpeg_demuxer_av_bsf_free(AVBSFContext * context)
{
 if(context != nullptr) av_bsf_free(&context);
}


int main(int argc, char * argv [])
{
 if(argc != 2)
 {
 std::cout << "Usage: " << argv[0] << " movie.mp4" << std::endl;
 exit(1);
 }

 // init the AV libraries
 //
 av_register_all();
 avformat_network_init();

 // allocate the AVFormatContext
 //
 AVFormatContext * format_context(nullptr);
 int const r1(avformat_open_input(
 &format_context
 , argv[1]
 , nullptr // input format
 , nullptr)); // options
 if(r1 != 0
 || format_context == nullptr)
 {
 throw std::bad_alloc();
 }

 auto f_format_context = std::unique_ptr<
 AVFormatContext
 , decltype(&ffmpeg_demuxer_avformat_context_free)>(
 format_context
 , &ffmpeg_demuxer_avformat_context_free);


 // now allocate a stream
 //
 if(avformat_find_stream_info(f_format_context.get(), nullptr) < 0)
 {
 throw std::runtime_error("ffmpeg: Could not find stream info");
 }

 auto f_video_stream_index = av_find_best_stream(
 f_format_context.get()
 , AVMEDIA_TYPE_VIDEO
 , -1 // wanted stream (any)
 , -1 // related stream (none)
 , nullptr // AVCodec *
 , 0); // flags
 if(f_video_stream_index < 0)
 {
 throw std::runtime_error("ffmpeg: Could not find stream in input file");
 }
 if(static_cast<unsigned int="int">(f_video_stream_index) >= f_format_context->nb_streams)
 {
 throw std::range_error("ffmpeg: Stream index out of range");
 }

 auto f_stream = f_format_context->streams[f_video_stream_index];

 auto f_video_codec = f_stream->codecpar->codec_id;

 int f_bit_depth(0);
 switch(f_stream->codecpar->format)
 {
 case AV_PIX_FMT_YUV420P10LE:
 f_bit_depth = 10;
 break;

 case AV_PIX_FMT_YUV420P12LE:
 f_bit_depth = 12;
 break;

 default:
 f_bit_depth = 8;
 break;

 }

 bool f_mp4_h264 = f_video_codec == AV_CODEC_ID_H264 && (
 strcmp(f_format_context->iformat->long_name, "QuickTime / MOV") == 0
 || strcmp(f_format_context->iformat->long_name, "FLV (Flash Video)") == 0
 || strcmp(f_format_context->iformat->long_name, "Matroska / WebM") == 0
 );

 if(f_mp4_h264)
 {
 AVBitStreamFilter const * bsf_stream_filter(av_bsf_get_by_name("h264_mp4toannexb"));
 if(bsf_stream_filter == nullptr)
 {
 throw std::runtime_error("av_bsf_get_by_name(\"h264_mp4toannexb\") failed");
 }
 AVBSFContext * bsf_context(nullptr);
 int const r2(av_bsf_alloc(bsf_stream_filter, &bsf_context));
 if(r2 < 0
 || bsf_context == nullptr)
 {
 throw std::bad_alloc();
 }
 auto f_bsf_context = std::unique_ptr<
 AVBSFContext
 , decltype(&ffmpeg_demuxer_av_bsf_free)>(
 bsf_context
 , &ffmpeg_demuxer_av_bsf_free);
 f_bsf_context->par_in = f_stream->codecpar;
 if(av_bsf_init(f_bsf_context.get()) < 0)
 {
 throw std::runtime_error("av_bsf_init() failed");
 }
 }

 return 0;
}
</unsigned></memory></iostream>

So. Am I misreading the documentation or misusing one of the free/close function ? I don't think that the
AVBSFContextitself gets released when I close theAVFormatContext, but I may be mistaken ?

I won't put "C" as a tag since it will get removed even though this applies to C. It's not because I use C++ that I get a double free (i.e. it happens in the ffmpeg C library).


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Draw text ffmpeg does not end when the word ends
25 juin 2018, par Kion DungIt works very well. But it can not end the video while the text has run out. And it runs forever. The bottom is my code. It has gaps with the background image forever. I want to stop it when the text is over. please complete it help me.
ffmpeg -loop 1 -i "C:\Users\Cu\Desktop\Lam\Lam\a.jpg" -i "C:\Users\Cu\Desktop\Lam\Lam\a.mp3" -vf drawtext='fontfile="Arial"\:style=bold:fontsize=70:textfile="C\:/Users/CuEm/Desktop/91990756.txt":fontcolor=#FFFFFF':x=0:y=h-20*t,format=yuv420p,scale=852x480,setsar=1:1 -vcodec libx264 -b:v 1000k -preset superfast "C:\Users\Cu\Desktop\b_o.mp4" -
rename files for language_REGION according to the standard ISO_3166-1 (http://en.wikipedia.org/wiki/ISO_3166-1), for Taiwan tha language is Chinese (zh) and the region is Taiwan (TW)
6 septembre 2012, par Cotom localization/messages_pt_BR.js m localization/messages_pt_PT.js m localization/messages_zh_TW.js rename files for language_REGION according to the standard ISO_3166-1 (http://en.wikipedia.org/wiki/ISO_3166-1), for Taiwan tha language is Chinese (zh) and the region is Taiwan (...)
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