avformat/http: Add short_seek_size option

In 45bfe8b838, short_seek_threshold was removed
from the public AVIO struct. Although this option was private and not intended
to be used by public API users, it was nonetheless, because it provided functionality
that could otherwise not be gained via public API.

This was especially important for networked I/O like HTTP, where the internal
size for lavf could be way to small depending on the specifics of a user's
usecase, such as reading interlavd media files from cloud storage.

Add an AVOption to make this functionality accessible to the HTTP client.

Signed-off-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>

libavformat/http.c

@@ -126,6 +126,7 @@ typedef struct HTTPContext {
     int is_multi_client;
     HandshakeState handshake_step;
     int is_connected_server;
+    int short_seek_size;
 } HTTPContext;
 
 #define OFFSET(x) offsetof(HTTPContext, x)
@@ -167,6 +168,7 @@ static const AVOption options[] = {
     { "listen", "listen on HTTP", OFFSET(listen), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 2, D | E },
     { "resource", "The resource requested by a client", OFFSET(resource), AV_OPT_TYPE_STRING, { .str = NULL }, 0, 0, E },
     { "reply_code", "The http status code to return to a client", OFFSET(reply_code), AV_OPT_TYPE_INT, { .i64 = 200}, INT_MIN, 599, E},
+    { "short_seek_size", "Threshold to favor readahead over seek.", OFFSET(short_seek_size), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, D },
     { NULL }
 };
 
@@ -1842,6 +1844,8 @@ static int http_get_file_handle(URLContext *h)
 static int http_get_short_seek(URLContext *h)
 {
     HTTPContext *s = h->priv_data;
+    if (s->short_seek_size >= 1)
+        return s->short_seek_size;
     return ffurl_get_short_seek(s->hd);
 }
 

libavformat/version.h

@@ -33,7 +33,7 @@
 // Also please add any ticket numbers that you believe might be affected here
 #define LIBAVFORMAT_VERSION_MAJOR  59
 #define LIBAVFORMAT_VERSION_MINOR   9
-#define LIBAVFORMAT_VERSION_MICRO 100
+#define LIBAVFORMAT_VERSION_MICRO 101
 
 #define LIBAVFORMAT_VERSION_INT AV_VERSION_INT(LIBAVFORMAT_VERSION_MAJOR, \
                                                LIBAVFORMAT_VERSION_MINOR, \