On Tue, Oct 25, 2011 at 11:35 PM, Anton Khirnov <[email protected]> wrote:
>
> On Tue, 25 Oct 2011 20:09:41 -0700, Alex Converse <[email protected]> 
> wrote:
>> On Tue, Oct 25, 2011 at 7:22 PM, Alex Converse <[email protected]> 
>> wrote:
>> > On Sun, Jun 19, 2011 at 1:42 PM, Anton Khirnov <[email protected]> wrote:
>> >> Module: libav
>> >> Branch: release/0.7
>> >> Commit: 05e84c95c7f0543553af8f0ebd50fb5604e7e2ff
>> >>
>> >> Author:    Anton Khirnov <[email protected]>
>> >> Committer: Anton Khirnov <[email protected]>
>> >> Date:      Sun May 22 08:37:25 2011 +0200
>> >>
>> >> lavf: add avformat_open_input() as a replacement for av_open_input_*
>> >>
>> >> Add support for demuxer private options.
>> >>
>> >
>> > This seems to do scary things...
>> >
>> >> ---
>> >>
>> >>  libavformat/avformat.h |   22 ++++++++++
>> >>  libavformat/options.c  |   28 +++++++++++++
>> >>  libavformat/utils.c    |  104 
>> >> +++++++++++++++++++++++++++++++++++++++++++++++-
>> >>  3 files changed, 153 insertions(+), 1 deletions(-)
>> >>
>> >> diff --git a/libavformat/avformat.h b/libavformat/avformat.h
>> >> index 2b5b50e..56a9d57 100644
>> > [...]
>> >> --- a/libavformat/utils.c
>> >> +++ b/libavformat/utils.c
>> >> @@ -605,6 +605,107 @@ int av_open_input_file(AVFormatContext **ic_ptr, 
>> >> const char *filename,
>> > [...]
>> >> +/* open input file and probe the format if necessary */
>> >> +static int init_input(AVFormatContext *s, const char *filename)
>> >> +{
>> >> +    int ret;
>> >> +    AVProbeData pd = {filename, NULL, 0};
>> >> +
>> >> +    if (s->pb) {
>> >> +        s->flags |= AVFMT_FLAG_CUSTOM_IO;
>> >> +        if (!s->iformat)
>> >> +            return av_probe_input_buffer(s->pb, &s->iformat, filename, 
>> >> s, 0, 0);
>> >> +        else if (s->iformat->flags & AVFMT_NOFILE)
>> >> +            return AVERROR(EINVAL);
>> >> +        return 0;
>> >> +    }
>> >> +
>> >> +    if ( (s->iformat && s->iformat->flags & AVFMT_NOFILE) ||
>> >> +        (!s->iformat && (s->iformat = av_probe_input_format(&pd, 0))))
>> >> +        return 0;
>> >
>> > Why are we probing with max score 0 here? Why are we probing at all here?
>> >
>>
>> My apologies about this part... is_opened = 0 here
>>
>>     while ((fmt1 = av_iformat_next(fmt1))) {
>>         if (!is_opened == !(fmt1->flags & AVFMT_NOFILE))
>>             continue;
>>
>>
>> >> +
>> >> +    if ((ret = avio_open(&s->pb, filename, AVIO_FLAG_READ)) < 0)
>> >> +       return ret;
>> >> +    if (s->iformat)
>> >> +        return 0;
>> >> +    return av_probe_input_buffer(s->pb, &s->iformat, filename, s, 0, 0);
>> >> +}
>> >> +
>> >> +int avformat_open_input(AVFormatContext **ps, const char *filename, 
>> >> AVInputFormat *fmt, AVDictionary **options)
>> >> +{
>> >> +    AVFormatContext *s = *ps;
>> >> +    int ret = 0;
>> >> +    AVFormatParameters ap = { 0 };
>> >> +    AVDictionary *tmp = NULL;
>> >> +
>> >> +    if (!s && !(s = avformat_alloc_context()))
>> >> +        return AVERROR(ENOMEM);
>> >> +    if (fmt)
>> >> +        s->iformat = fmt;
>> >> +
>> >> +    if (options)
>> >> +        av_dict_copy(&tmp, *options, 0);
>> >> +
>> >> +    if ((ret = av_opt_set_dict(s, &tmp)) < 0)
>> >> +        goto fail;
>> >> +
>> >> +    if ((ret = init_input(s, filename)) < 0)
>> >> +        goto fail;
>> >> +
>> >> +    /* check filename in case an image number is expected */
>> >> +    if (s->iformat->flags & AVFMT_NEEDNUMBER) {
>> >> +        if (!av_filename_number_test(filename)) {
>> >> +            ret = AVERROR(EINVAL);
>> >> +            goto fail;
>> >> +        }
>> >> +    }
>> >> +
>> >> +    s->duration = s->start_time = AV_NOPTS_VALUE;
>> >> +    av_strlcpy(s->filename, filename, sizeof(s->filename));
>> >> +
>> >> +    /* allocate private data */
>> >> +    if (s->iformat->priv_data_size > 0) {
>> >> +        if (!(s->priv_data = av_mallocz(s->iformat->priv_data_size))) {
>> >> +            ret = AVERROR(ENOMEM);
>> >> +            goto fail;
>> >> +        }
>> >> +        if (s->iformat->priv_class) {
>> >> +            *(const AVClass**)s->priv_data = s->iformat->priv_class;
>> >> +            av_opt_set_defaults(s->priv_data);
>> >> +            if ((ret = av_opt_set_dict(s->priv_data, &tmp)) < 0)
>> >> +                goto fail;
>> >> +        }
>> >> +    }
>> >> +
>> >> +    /* e.g. AVFMT_NOFILE formats will not have a AVIOContext */
>> >> +    if (s->pb)
>> >> +        ff_id3v2_read(s, ID3v2_DEFAULT_MAGIC);
>> >> +
>> >> +    if (s->iformat->read_header)
>> >> +        if ((ret = s->iformat->read_header(s, &ap)) < 0)
>> >
>> > read_header() often uses s->pb
>> >
>>
>> still curious about this part
>>
>
> read_header() only uses s->pb if it's not an AVFMT_NOFILE format,
> so s->pb is non-NULL.
>

Makes sense, thanks.
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