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ffmpeg: don't pass pointer as hexadecimal string

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Casting a pointer to some sort of integer and formatting it into a
string isn't valid.  A pointer derived from this hex string won't work
reliably.  Since ffmpeg doesn't provide a nice API for passing our
pointer, we have to think of a different hack: ffmpeg passes the exact
URL pointer to mpdurl_open(), and we can make this string part of a
struct.  This reduces the problem to casting the string back to the
struct.

This is still a workaround, but this is "sort of portable", unless the
ffmpeg people start messing with the URL pointer (which would be valid
according to the API definition).
This commit is contained in:
Max Kellermann 2008-10-21 18:12:56 +02:00
parent e4df17f611
commit a7888c4998
1 changed files with 27 additions and 20 deletions
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47
src/inputPlugins/ffmpeg_plugin.c
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@ -50,26 +50,34 @@ typedef struct {
} BasePtrs;
typedef struct {
/** hack - see url_to_base() */
char url[8];
struct decoder *decoder;
InputStream *input;
} FopsHelper;
static int mpdurl_open(URLContext *h, const char *filename, int flags)
/**
* Convert a faked mpd:// URL to a FopsHelper structure. This is a
* hack because ffmpeg does not provide a nice API for passing a
* user-defined pointer to mpdurl_open().
*/
static FopsHelper *url_to_base(const char *url)
{
uint32_t ptr;
FopsHelper *base;
if (strlen(filename) == (8+8)) {
errno = 0;
ptr = (uint32_t) strtoll(filename + 6, NULL, 16);
if (errno == 0 && ptr != 0) {
base = (FopsHelper *) ptr;
h->priv_data = base;
h->is_streamed = (base->input->seekable ? 0 : 1);
return 0;
}
}
FATAL("Invalid format %s:%d\n", filename, flags);
return -1;
union {
const char *in;
FopsHelper *out;
} u = { .in = url };
return u.out;
}
static int mpdurl_open(URLContext *h, const char *filename,
mpd_unused int flags)
{
FopsHelper *base = url_to_base(filename);
h->priv_data = base;
h->is_streamed = (base->input->seekable ? 0 : 1);
return 0;
}
static int mpdurl_read(URLContext *h, unsigned char *buf, int size)
@ -137,8 +145,9 @@ static int ffmpeg_helper(InputStream *input, int (*callback)(BasePtrs *ptrs),
AVCodec *aCodec;
int ret, audioStream;
unsigned i;
FopsHelper fopshelp;
char url[24];
FopsHelper fopshelp = {
.url = "mpd://X", /* only the mpd:// prefix matters */
};
fopshelp.input = input;
if (ptrs && ptrs->decoder) {
@ -148,9 +157,7 @@ static int ffmpeg_helper(InputStream *input, int (*callback)(BasePtrs *ptrs),
}
//ffmpeg works with ours "fileops" helper
sprintf(url, "mpd://0x%8x", (unsigned int) &fopshelp);
if (av_open_input_file(&pFormatCtx, url, NULL, 0, NULL)!=0) {
if (av_open_input_file(&pFormatCtx, fopshelp.url, NULL, 0, NULL)!=0) {
ERROR("Open failed!\n");
return -1;
}