#1913: Why file fails to open when saving frames from one file to other without
any encoding/decoding?
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Reporter: theateist | Type: defect
Status: new | Priority: important
Component: avcodec | Version: unspecified
Keywords: | Blocked By:
Blocking: | Reproduced by developer: 1
Analyzed by developer: 1 |
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I started learning ffmpeg and for practice I use the following code to
just save all frames from inFileName to outFileName. At first sight it
success but the file fails to open with WindowsMediaPlayer. VLC Player
opens it but I see strange colorful stripes at the bottom. In addition,
the pix_fmt of inFileName is pal8 and of the outFileName is changed to
bgr24, although I construct outFormatCtx the same as inFormatCtx.
What is the problem and why I get different pix_fmt in out file?
Thanks
{{{
const char* inFileName = "C:\\FlickAnimation.avi";
const char* outFileName = "c:\\out.avi";
const char* outFileType = "avi";
av_register_all();
AVFormatContext* inFormatCtx = NULL;
int err = avformat_open_input(&inFormatCtx, inFileName, NULL,
NULL);
if (err < 0) exit(1);
err = av_find_stream_info(inFormatCtx);
if (err < 0) exit(1);
// Find video stream
int videoStreamIndex = -1;
for (unsigned int i = 0; i < inFormatCtx->nb_streams; ++i)
{
if (inFormatCtx->streams[i] &&
inFormatCtx->streams[i]->codec &&
inFormatCtx->streams[i]->codec->codec_type
== AVMEDIA_TYPE_VIDEO)
{
videoStreamIndex = i;
break;
}
}
if (videoStreamIndex == -1) exit(1);
AVOutputFormat* outFormat = av_guess_format(outFileType, NULL,
NULL);
if (!outFormat) exit(1);
AVFormatContext* outFormatCtx = NULL;
err = avformat_alloc_output_context2(&outFormatCtx, outFormat,
NULL, NULL);
if (err < 0 || !outFormatCtx) exit(1);
err = avio_open(&outFormatCtx->pb, outFileName, AVIO_FLAG_WRITE);
if (err < 0) exit(1);
// Create and initiate output stream
AVStream* outStream = av_new_stream(outFormatCtx, 0);
AVStream const* const inStream =
inFormatCtx->streams[videoStreamIndex];
AVCodec* codec = NULL;
avcodec_get_context_defaults3(outStream->codec,
inStream->codec->codec);
outStream->codec->coder_type = AVMEDIA_TYPE_VIDEO;
outStream->codec->sample_aspect_ratio =
outStream->sample_aspect_ratio = inStream->sample_aspect_ratio;
outStream->disposition = inStream->disposition;
outStream->codec->bits_per_raw_sample =
inStream->codec->bits_per_raw_sample;
outStream->codec->chroma_sample_location =
inStream->codec->chroma_sample_location;
outStream->codec->codec_id = inStream->codec->codec_id;
outStream->codec->codec_type = inStream->codec->codec_type;
outStream->codec->bit_rate = inStream->codec->bit_rate;
outStream->codec->rc_max_rate = inStream->codec->rc_max_rate;
outStream->codec->rc_buffer_size =
inStream->codec->rc_buffer_size;
if (!outStream->codec->codec_tag)
{
if (! outFormatCtx->oformat->codec_tag
|| av_codec_get_id (outFormatCtx->oformat->codec_tag,
inStream->codec->codec_tag) == outStream->codec->codec_id
|| av_codec_get_tag(outFormatCtx->oformat->codec_tag,
inStream->codec->codec_id) <= 0)
outStream->codec->codec_tag =
inStream->codec->codec_tag;
}
size_t extra_size_alloc = (inStream->codec->extradata_size > 0) ?
(inStream->codec->extradata_size + FF_INPUT_BUFFER_PADDING_SIZE) : 0;
if (extra_size_alloc)
{
outStream->codec->extradata =
(uint8_t*)av_malloc(extra_size_alloc);
memcpy(outStream->codec->extradata,
inStream->codec->extradata, inStream->codec->extradata_size);
}
outStream->codec->extradata_size =
inStream->codec->extradata_size;
AVRational input_time_base = inStream->time_base;
AVRational frameRate;
frameRate.num = inStream->r_frame_rate.num;
frameRate.den = inStream->r_frame_rate.den;
outStream->r_frame_rate = frameRate;
outStream->codec->time_base = inStream->codec->time_base;
outStream->codec->pix_fmt = inStream->codec->pix_fmt;
outStream->codec->width = inStream->codec->width;
outStream->codec->height = inStream->codec->height;
outStream->codec->has_b_frames = inStream->codec->has_b_frames;
if (!outStream->codec->sample_aspect_ratio.num)
{
AVRational r0 = {0, 1};
outStream->codec->sample_aspect_ratio =
outStream->sample_aspect_ratio = inStream->sample_aspect_ratio.num ?
inStream->sample_aspect_ratio :
inStream->codec->sample_aspect_ratio.num ?
inStream->codec->sample_aspect_ratio : r0;
}
avformat_write_header(outFormatCtx, NULL);
AVPacket packet;
while(av_read_frame(inFormatCtx, &packet)>=0)
{
if (packet.stream_index == videoStreamIndex)
{
err = av_interleaved_write_frame(outFormatCtx,
&packet);
if (err < 0) exit(1);
}
av_free_packet(&packet);
}
av_write_trailer(outFormatCtx);
avio_close(outFormatCtx->pb);
avformat_free_context(outFormatCtx);
av_close_input_file(inFormatCtx);
}}}
d
--
Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/1913>
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