[Libav-user] avcodec_close() crash
Андрей
ashvyrkin at gosniias.ru
Fri Jun 14 16:27:21 CEST 2013
06.06.2013 7:53, Андрей пишет:
> 05.06.2013 14:39, Andrey Utkin пишет:
>> 2013/6/5 Андрей <ashvyrkin at gosniias.ru>:
>>> I use to compile the 32-bit version of ffmpeg visual studio 2012. I
>>> used the
>>> latter for now build from 5/29/13.
>>> This is my test code that reproduces the problem:
>>>
>>> avcodec_register_all();
>>>
>>> int width = 764, height = 480;
>>> int got_output;
>>> AVFrame *frame;
>>> AVPacket pkt;
>>> AVCodec *codec;
>>> AVCodecContext *c = NULL;
>>>
>>> while(1)
>>> {
>>> frame = avcodec_alloc_frame();
>>> if (!frame) {
>>> fprintf(stderr, "Could not allocate video frame\n");
>>> return -1;
>>> }
>>> frame->format = AV_PIX_FMT_YUV420P;
>>> frame->width = width;
>>> frame->height = height;
>>>
>>> /* the image can be allocated by any means and
>>> av_image_alloc() is
>>> * just the most convenient way if av_malloc() is to be
>>> used */
>>> int ret = av_image_alloc(frame->data, frame->linesize, width,
>>> height,
>>> AV_PIX_FMT_YUV420P, 1);
>>> if (ret < 0) {
>>> fprintf(stderr, "Could not allocate raw picture
>>> buffer\n");
>>> av_freep(&frame->data[0]);
>>> avcodec_free_frame(&frame);
>>> return -1;
>>> }
>>>
>>> /* find the mpeg4 video encoder */
>>> codec = avcodec_find_encoder(AV_CODEC_ID_MPEG4);
>>> if (!codec) {
>>> fprintf(stderr, "Codec not found\n");
>>> return -1;
>>> }
>>>
>>> c = avcodec_alloc_context3(codec);
>>> if (!c) {
>>> fprintf(stderr, "Could not allocate video codec
>>> context\n");
>>> return -1;
>>> }
>>>
>>> /* put sample parameters */
>>> c->profile = FF_PROFILE_MPEG4_SIMPLE;
>>> /* resolution must be a multiple of two */
>>> c->width = width;
>>> c->height = height;
>>> /* frames per second */
>>> c->time_base.den = 25;
>>> c->time_base.num = 1;
>>> c->gop_size = 25; /* emit one intra frame every 25 frames */
>>> c->pix_fmt = AV_PIX_FMT_YUV420P;
>>> c->qmax = 4;
>>> c->qmin = 4;
>>>
>>> /* open it */
>>> if (avcodec_open2(c, codec, NULL) < 0) {
>>> fprintf(stderr, "Could not open codec\n");
>>> avcodec_close(c);
>> You shouldn't avcodec_close() here. I think this can cause a problem.
>>
>>> av_free(c);
>>> return -1;
>>> }
>>>
>>> for(int k = 0; k < 30; k++)
>>> {
>>> av_init_packet(&pkt);
>>> pkt.data = NULL; // packet data will be allocated by
>>> the
>>> encoder
>>> pkt.size = 0;
>>>
>>> frame->pts = c->frame_number;
>>>
>>> /* encode the image */
>>> if (avcodec_encode_video2(c, &pkt, frame, &got_output)
>>> < 0) {
>>> fprintf(stderr, "Error encoding frame\n");
>>> return -1;
>>> }
>>>
>>> if (got_output) {
>>> av_free_packet(&pkt);
>>> }
>>> }
>>>
>>> if(c)
>>> {
>>> avcodec_close(c);
>>> av_free(c);
>> Can't say for sure, but av_free() seems redundant.
>>
>>> }
>>> if(frame)
>>> {
>>> av_freep(&frame->data[0]);
>>> avcodec_free_frame(&frame);
>> Maybe there also something is redundant.
>>
>>> }
>>> }
>>>
>>> When you call function avcodec_close () throws an exception. Such an
>>> error
>>> is detected on the MPEG4 codec with a frame width in the range
>>> 754-767 at an
>>> altitude of 480. Perhaps at other resolutions, too. Help solve the
>>> problem.
>>> ...sorry for bad english
>> You have more than one call to avcodec_close(), do you know, which one
>> is executed?
>>
>> Your code snippet should be easily compiled on linux, there you can
>> use valgrind memcheck tool, which makes debugging easy.
>> Also i suggest you to re-read avcodec.h and avformat.h for
>> explanations on how to release context objects correclty, some places
>> in your code are suspicious for me.
>>
>> --
>> Andrey Utkin
>> _______________________________________________
>> Libav-user mailing list
>> Libav-user at ffmpeg.org
>> http://ffmpeg.org/mailman/listinfo/libav-user
> Ok, for now I'm using video_encode_example from decoding_encoding.c
> example:
>
> AVCodec *codec;
> AVCodecContext *c = NULL;
> int i, ret, x, y, got_output;
> AVFrame *frame;
> AVPacket pkt;
>
> /* register all the codecs */
> avcodec_register_all();
>
> /* find the mpeg1 video encoder */
> codec = avcodec_find_encoder(AV_CODEC_ID_MPEG4);
> if (!codec) {
> fprintf(stderr, "Codec not found\n");
> exit(1);
> }
>
> c = avcodec_alloc_context3(codec);
> if (!c) {
> fprintf(stderr, "Could not allocate video codec context\n");
> exit(1);
> }
>
> /* put sample parameters */
> c->bit_rate = 400000;
> /* resolution must be a multiple of two */
> c->width = 764;
> c->height = 480;
> /* frames per second */
> c->time_base.den = 25;
> c->time_base.num = 1;
> c->gop_size = 10; /* emit one intra frame every ten frames */
> c->max_b_frames = 1;
> c->pix_fmt = AV_PIX_FMT_YUV420P;
>
> /* open it */
> if (avcodec_open2(c, codec, NULL) < 0) {
> fprintf(stderr, "Could not open codec\n");
> exit(1);
> }
>
> frame = avcodec_alloc_frame();
> if (!frame) {
> fprintf(stderr, "Could not allocate video frame\n");
> exit(1);
> }
> frame->format = c->pix_fmt;
> frame->width = c->width;
> frame->height = c->height;
>
> /* the image can be allocated by any means and av_image_alloc() is
> * just the most convenient way if av_malloc() is to be used */
> ret = av_image_alloc(frame->data, frame->linesize, c->width,
> c->height,
> c->pix_fmt, 32);
> if (ret < 0) {
> fprintf(stderr, "Could not allocate raw picture buffer\n");
> exit(1);
> }
>
> /* encode 1 second of video */
> for(i=0;i<25;i++) {
> av_init_packet(&pkt);
> pkt.data = NULL; // packet data will be allocated by the
> encoder
> pkt.size = 0;
>
> fflush(stdout);
> /* prepare a dummy image */
> /* Y */
> for(y=0;y<c->height;y++) {
> for(x=0;x<c->width;x++) {
> frame->data[0][y * frame->linesize[0] + x] = x + y + i
> * 3;
> }
> }
>
> /* Cb and Cr */
> for(y=0;y<c->height/2;y++) {
> for(x=0;x<c->width/2;x++) {
> frame->data[1][y * frame->linesize[1] + x] = 128 + y +
> i * 2;
> frame->data[2][y * frame->linesize[2] + x] = 64 + x +
> i * 5;
> }
> }
>
> frame->pts = i;
>
> /* encode the image */
> ret = avcodec_encode_video2(c, &pkt, frame, &got_output);
> if (ret < 0) {
> fprintf(stderr, "Error encoding frame\n");
> exit(1);
> }
>
> if (got_output) {
> av_free_packet(&pkt);
> }
> }
>
> avcodec_close(c);
> av_free(c);
> av_freep(&frame->data[0]);
> avcodec_free_frame(&frame);
>
> The problem is that the context is not released correctly when the
> resolution is 764x480 and some other resolutions. If you use a
> different codec instead of MPEG4, such as H264, no error occurs if any
> resolution. I use the assembly under windows and unfortunately I do
> not have the possibility to compile the example under Linux to
> pinpoint the cause of the fall.
*In the latest build of 14.06.13 the problem is solved.*
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