Looking for feedback on this patch, in particular the use of the
'keys' dictionary within the MOVContext structure.
With the patch FFmpeg can now 'find' the metadata in ARRI's sample
footage see here:
http://www.arri.com/camera/alexa/learn/alexa_sample_footage/
Thanks
Kevin
From 57feefffff09b636d8d80d3afe7dca20175ddb51 Mon Sep 17 00:00:00 2001
From: Kevin Wheatley <kevin.j.wheat...@gmail.com>
Date: Thu, 3 Sep 2015 15:58:49 +0100
Subject: [PATCH] RFC: Extend metadata handling to read in the keys from the 'keys' atom
---
libavformat/isom.h | 1 +
libavformat/mov.c | 63 ++++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 64 insertions(+), 0 deletions(-)
diff --git a/libavformat/isom.h b/libavformat/isom.h
index aee9d6e..8c20ec9 100644
--- a/libavformat/isom.h
+++ b/libavformat/isom.h
@@ -206,6 +206,7 @@ typedef struct MOVContext {
void *audible_fixed_key;
int audible_fixed_key_size;
struct AVAES *aes_decrypt;
+ AVDictionary *keys_d; // Use a dictionary as an array a little bit ugly
} MOVContext;
int ff_mp4_read_descr_len(AVIOContext *pb);
diff --git a/libavformat/mov.c b/libavformat/mov.c
index 45367d3..1cf50bb 100644
--- a/libavformat/mov.c
+++ b/libavformat/mov.c
@@ -265,6 +265,7 @@ static int mov_read_udta_string(MOVContext *c, AVIOContext *pb, MOVAtom atom)
uint32_t data_type = 0, str_size, str_size_alloc;
int (*parse)(MOVContext*, AVIOContext*, unsigned, const char*) = NULL;
int raw = 0;
+ AVDictionaryEntry *entry = NULL;
switch (atom.type) {
case MKTAG( '@','P','R','M'): key = "premiere_version"; raw = 1; break;
@@ -351,6 +352,13 @@ static int mov_read_udta_string(MOVContext *c, AVIOContext *pb, MOVAtom atom)
case MKTAG(0xa9,'w','r','n'): key = "warning"; break;
case MKTAG(0xa9,'w','r','t'): key = "composer"; break;
case MKTAG(0xa9,'x','y','z'): key = "location"; break;
+ default:
+ snprintf(key2, sizeof(key2), "%08x", atom.type);
+ entry = av_dict_get(c->keys_d, key2, entry, 0);
+ if (entry)
+ key = entry->value;
+ av_log(c->fc, AV_LOG_TRACE, "Attempting to match unknown atom type %08x %s in keys => '%s'\n", atom.type, key2, key);
+ break;
}
retry:
if (c->itunes_metadata && atom.size > 8) {
@@ -3184,6 +3192,58 @@ static int mov_read_meta(MOVContext *c, AVIOContext *pb, MOVAtom atom)
return 0;
}
+static int mov_read_keys(MOVContext *c, AVIOContext *pb, MOVAtom atom)
+{
+ AVDictionaryEntry *entry = NULL;
+ uint32_t key_count, key_size, key_namespace, key_num;
+ char *key_str;
+ char key_num_str[8+1] = { 0 }; // Use hexadecimal string of a 32 bit integer + terminator
+ int ret;
+
+ avio_r8(pb); /* version */
+ avio_rb24(pb); /* flags */
+ key_count = avio_rb32(pb);
+
+ av_log(c->fc, AV_LOG_VERBOSE,
+ "Reading keys sz: %"PRId64" %u\n", atom.size, key_count);
+
+ key_num = 1; // Keys are numbered from 1 and refered to in the ilst following.
+ while (key_count--) {
+ key_size = avio_rb32(pb) - 8;
+ key_namespace = avio_rl32(pb);
+ if (key_namespace == MKTAG('m','d','t','a')) {
+ key_str = av_malloc(key_size + 1); /* Add null terminator */
+ if (!key_str) {
+ return AVERROR(ENOMEM);
+ }
+
+ ret = ffio_read_size(pb, key_str, key_size);
+ if (ret < 0) {
+ av_freep(&key_str);
+ return ret;
+ }
+
+ key_str[key_size] = 0;
+ if (key_str[0]) {
+ snprintf(key_num_str, sizeof(key_num_str), "%08x", av_bswap32(key_num));
+ av_dict_set(&(c->keys_d), key_num_str, key_str, 0);
+ }
+ av_freep(&key_str);
+ } else {
+ // Don't know what to do with other namespaces... ignore
+ avio_seek(pb, key_size, SEEK_CUR);
+ }
+ ++key_num;
+ }
+
+ while (entry = av_dict_get(c->keys_d, "", entry, AV_DICT_IGNORE_SUFFIX)) {
+ av_log(c->fc, AV_LOG_TRACE,
+ "Read metadata key %s: '%s'\n", entry->key, entry->value);
+ }
+
+ return 0;
+}
+
static int mov_read_tkhd(MOVContext *c, AVIOContext *pb, MOVAtom atom)
{
int i;
@@ -3786,6 +3846,7 @@ static const MOVParseTableEntry mov_default_parse_table[] = {
{ MKTAG('h','d','l','r'), mov_read_hdlr },
{ MKTAG('i','l','s','t'), mov_read_ilst },
{ MKTAG('j','p','2','h'), mov_read_jp2h },
+{ MKTAG('k','e','y','s'), mov_read_keys },
{ MKTAG('m','d','a','t'), mov_read_mdat },
{ MKTAG('m','d','h','d'), mov_read_mdhd },
{ MKTAG('m','d','i','a'), mov_read_default },
@@ -4203,6 +4264,8 @@ static int mov_read_close(AVFormatContext *s)
av_freep(&mov->fragment_index_data);
av_freep(&mov->aes_decrypt);
+
+ av_dict_free(&mov->keys_d);
return 0;
}
--
1.7.1
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