[FFmpeg-devel] [PATCH 2/3] ffprobe: replace fmt callback with str callback.
Clément Bœsch
ubitux at gmail.com
Mon Sep 12 22:44:22 CEST 2011
On Sun, Sep 11, 2011 at 11:21:50PM +0200, Clément Bœsch wrote:
[...]
> > Could you benchmark it? allocing/freeing a buffer for every single
> > print looks quite expensive.
> >
>
> With a 250M media input:
>
> av_asprintf/av_free: ~1.5sec
> 4096B stack buffer: ~1.1sec
>
> > Alternatively: you pass a buffer which is reallocated if and only when
> > needed, this would need some custom code.
> >
1.2sec with the "fast asprintf" version attached. I'll commit this in a
few days if no objection.
--
Clément B.
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From 978d84f3346f7470674a8c7730d7cbc44da872da Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Cl=C3=A9ment=20B=C5=93sch?= <ubitux at gmail.com>
Date: Mon, 12 Sep 2011 19:22:53 +0200
Subject: [PATCH] ffprobe: replace fmt callback with str callback.
Having a string callback is much more simpler than a variable args
one for writers to deal with, especially when dealing with escaping.
This patch also introduces a local fast_asprintf() function which is
similar to av_asprintf() but avoids reallocating at each print (leading
to a performance issue).
---
ffprobe.c | 64 +++++++++++++++++++++++++++++++++++++++++++++++++++---------
1 files changed, 54 insertions(+), 10 deletions(-)
diff --git a/ffprobe.c b/ffprobe.c
index 538120f..75df26c 100644
--- a/ffprobe.c
+++ b/ffprobe.c
@@ -137,8 +137,8 @@ struct writer {
const char *header, *footer;
void (*print_header)(const char *);
void (*print_footer)(const char *);
- void (*print_fmt_f)(const char *, const char *, ...);
void (*print_int_f)(const char *, int);
+ void (*print_str_f)(const char *, const char *);
void (*show_tags)(struct writer *w, AVDictionary *dict);
};
@@ -150,13 +150,9 @@ static void default_print_header(const char *section)
printf("[%s]\n", section);
}
-static void default_print_fmt(const char *key, const char *fmt, ...)
+static void default_print_str(const char *key, const char *value)
{
- va_list ap;
- va_start(ap, fmt);
- printf("%s=", key);
- vprintf(fmt, ap);
- va_end(ap);
+ printf("%s=%s", key, value);
}
static void default_print_int(const char *key, int value)
@@ -169,14 +165,54 @@ static void default_print_footer(const char *section)
printf("\n[/%s]", section);
}
+struct print_buf {
+ char *s;
+ int len;
+};
+
+static char *fast_asprintf(struct print_buf *pbuf, const char *fmt, ...)
+{
+ va_list va;
+ int len;
+
+ va_start(va, fmt);
+ len = vsnprintf(NULL, 0, fmt, va);
+ va_end(va);
+ if (len < 0)
+ goto fail;
+
+ if (pbuf->len < len) {
+ char *p = av_realloc(pbuf->s, len + 1);
+ if (!p)
+ goto fail;
+ pbuf->s = p;
+ pbuf->len = len;
+ }
+
+ va_start(va, fmt);
+ len = vsnprintf(pbuf->s, len + 1, fmt, va);
+ va_end(va);
+ if (len < 0)
+ goto fail;
+ return pbuf->s;
+
+fail:
+ av_freep(&pbuf->s);
+ pbuf->len = 0;
+ return NULL;
+}
+
/* Print helpers */
-#define print_fmt0(k, f, ...) w->print_fmt_f(k, f, __VA_ARGS__)
+#define print_fmt0(k, f, ...) do { \
+ if (fast_asprintf(&pbuf, f, __VA_ARGS__)) \
+ w->print_str_f(k, pbuf.s); \
+} while (0)
#define print_fmt( k, f, ...) do { \
if (w->item_sep) \
printf("%s", w->item_sep); \
- w->print_fmt_f(k, f, __VA_ARGS__); \
+ print_fmt0(k, f, __VA_ARGS__); \
} while (0)
#define print_int0(k, v) w->print_int_f(k, v)
@@ -194,6 +230,7 @@ static void show_packet(struct writer *w, AVFormatContext *fmt_ctx, AVPacket *pk
{
char val_str[128];
AVStream *st = fmt_ctx->streams[pkt->stream_index];
+ struct print_buf pbuf = {.s = NULL};
if (packet_idx)
printf("%s", w->items_sep);
@@ -210,6 +247,7 @@ static void show_packet(struct writer *w, AVFormatContext *fmt_ctx, AVPacket *pk
print_fmt("pos", "%"PRId64, pkt->pos);
print_fmt("flags", "%c", pkt->flags & AV_PKT_FLAG_KEY ? 'K' : '_');
w->print_footer("PACKET");
+ av_free(pbuf.s);
fflush(stdout);
}
@@ -227,10 +265,12 @@ static void show_packets(struct writer *w, AVFormatContext *fmt_ctx)
static void default_show_tags(struct writer *w, AVDictionary *dict)
{
AVDictionaryEntry *tag = NULL;
+ struct print_buf pbuf = {.s = NULL};
while ((tag = av_dict_get(dict, "", tag, AV_DICT_IGNORE_SUFFIX))) {
printf("\nTAG:");
print_str0(tag->key, tag->value);
}
+ av_free(pbuf.s);
}
static void show_stream(struct writer *w, AVFormatContext *fmt_ctx, int stream_idx)
@@ -240,6 +280,7 @@ static void show_stream(struct writer *w, AVFormatContext *fmt_ctx, int stream_i
AVCodec *dec;
char val_str[128];
AVRational display_aspect_ratio;
+ struct print_buf pbuf = {.s = NULL};
if (stream_idx)
printf("%s", w->items_sep);
@@ -307,6 +348,7 @@ static void show_stream(struct writer *w, AVFormatContext *fmt_ctx, int stream_i
w->show_tags(w, stream->metadata);
w->print_footer("STREAM");
+ av_free(pbuf.s);
fflush(stdout);
}
@@ -320,6 +362,7 @@ static void show_streams(struct writer *w, AVFormatContext *fmt_ctx)
static void show_format(struct writer *w, AVFormatContext *fmt_ctx)
{
char val_str[128];
+ struct print_buf pbuf = {.s = NULL};
w->print_header("FORMAT");
print_str0("filename", fmt_ctx->filename);
@@ -332,6 +375,7 @@ static void show_format(struct writer *w, AVFormatContext *fmt_ctx)
print_str("bit_rate", value_string(val_str, sizeof(val_str), fmt_ctx->bit_rate, unit_bit_per_second_str));
w->show_tags(w, fmt_ctx->metadata);
w->print_footer("FORMAT");
+ av_free(pbuf.s);
fflush(stdout);
}
@@ -380,8 +424,8 @@ static int open_input_file(AVFormatContext **fmt_ctx_ptr, const char *filename)
#define WRITER_FUNC(func) \
.print_header = func ## _print_header, \
.print_footer = func ## _print_footer, \
- .print_fmt_f = func ## _print_fmt, \
.print_int_f = func ## _print_int, \
+ .print_str_f = func ## _print_str, \
.show_tags = func ## _show_tags
static struct writer writers[] = {{
--
1.7.6.1
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