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[FFmpeg-devel,05/20] avformat/matroskaenc: Remove allocations for Attachments

Message ID 20200405155928.9323-6-andreas.rheinhardt@gmail.com
State Accepted
Commit 358b58cb290defe706dd2f5bae96b29321059dfe
Headers show
Series Matroska muxer patches
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Commit Message

Andreas Rheinhardt April 5, 2020, 3:59 p.m. UTC
If there are Attachments to write, the Matroska muxer currently
allocates two objects: An array that contains an entry for each
AttachedFile containing just the stream index of the corresponding
stream and the FileUID used for this AttachedFile; and a structure with
a pointer to said array and a counter for said array. These uids are
generated via code special to Attachments: It uses an AVLFG in the
normal and a sha of the attachment data in the bitexact case. (Said sha
requires an allocation, too.)

But now that an uid is generated for each stream in mkv_init(), there is
no need any more to use special code for generating the FileUIDs of
AttachedFiles: One can simply use the uid already generated for the
corresponding stream. And this makes the whole allocations of the
structures for AttachedFiles as well as the structures itself superfluous.
They have been removed.

In case AVFMT_FLAG_BITEXACT is set, the uids will be different from the
old ones which is the reason why the FATE-test lavf-mkv_attachment
needed to be updated. The old method had the drawback that two
AttachedFiles with the same data would have the same FileUID.
The new one doesn't.

Also notice that the dynamic buffer used to write the Attachments leaks
if an error happens when writing the buffer. By removing the
allocations potential sources of errors have been removed.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
---
This will be the last patch of my "remove allocations for"-series;
after this there won't be any allocations to remove any more.

 libavformat/matroskaenc.c     | 63 +++++------------------------------
 tests/ref/lavf/mkv_attachment |  4 +--
 2 files changed, 11 insertions(+), 56 deletions(-)
diff mbox series

Patch

diff --git a/libavformat/matroskaenc.c b/libavformat/matroskaenc.c
index b93c50cb01..135d5e3abd 100644
--- a/libavformat/matroskaenc.c
+++ b/libavformat/matroskaenc.c
@@ -50,7 +50,6 @@ 
 #include "libavutil/random_seed.h"
 #include "libavutil/rational.h"
 #include "libavutil/samplefmt.h"
-#include "libavutil/sha.h"
 #include "libavutil/stereo3d.h"
 
 #include "libavcodec/xiph.h"
@@ -105,16 +104,6 @@  typedef struct mkv_track {
     int64_t         ts_offset;
 } mkv_track;
 
-typedef struct mkv_attachment {
-    int             stream_idx;
-    uint32_t        fileuid;
-} mkv_attachment;
-
-typedef struct mkv_attachments {
-    mkv_attachment  *entries;
-    int             num_entries;
-} mkv_attachments;
-
 #define MODE_MATROSKAv2 0x01
 #define MODE_WEBM       0x02
 
@@ -141,7 +130,6 @@  typedef struct MatroskaMuxContext {
     mkv_seekhead    seekhead;
     mkv_cues        cues;
     mkv_track       *tracks;
-    mkv_attachments *attachments;
 
     AVPacket        cur_audio_pkt;
 
@@ -403,10 +391,6 @@  static void mkv_deinit(AVFormatContext *s)
     ffio_free_dyn_buf(&mkv->tags_bc);
 
     av_freep(&mkv->cues.entries);
-    if (mkv->attachments) {
-        av_freep(&mkv->attachments->entries);
-        av_freep(&mkv->attachments);
-    }
     av_freep(&mkv->tracks);
 }
 
@@ -1617,15 +1601,18 @@  static int mkv_write_tags(AVFormatContext *s)
     }
 
     if (mkv->have_attachments && mkv->mode != MODE_WEBM) {
-        for (i = 0; i < mkv->attachments->num_entries; i++) {
-            mkv_attachment *attachment = &mkv->attachments->entries[i];
-            AVStream *st = s->streams[attachment->stream_idx];
+        for (i = 0; i < s->nb_streams; i++) {
+            mkv_track *track = &mkv->tracks[i];
+            AVStream *st = s->streams[i];
+
+            if (st->codecpar->codec_type != AVMEDIA_TYPE_ATTACHMENT)
+                continue;
 
             if (!mkv_check_tag(st->metadata, MATROSKA_ID_TAGTARGETS_ATTACHUID))
                 continue;
 
             ret = mkv_write_tag(s, st->metadata, MATROSKA_ID_TAGTARGETS_ATTACHUID,
-                                attachment->fileuid, NULL);
+                                track->uid, NULL);
             if (ret < 0)
                 return ret;
         }
@@ -1645,18 +1632,11 @@  static int mkv_write_attachments(AVFormatContext *s)
 {
     MatroskaMuxContext *mkv = s->priv_data;
     AVIOContext *dyn_cp = NULL, *pb = s->pb;
-    AVLFG c;
     int i, ret;
 
     if (!mkv->have_attachments)
         return 0;
 
-    mkv->attachments = av_mallocz(sizeof(*mkv->attachments));
-    if (!mkv->attachments)
-        return AVERROR(ENOMEM);
-
-    av_lfg_init(&c, av_get_random_seed());
-
     mkv_add_seekhead_entry(mkv, MATROSKA_ID_ATTACHMENTS, avio_tell(pb));
 
     ret = start_ebml_master_crc32(&dyn_cp, mkv);
@@ -1664,20 +1644,14 @@  static int mkv_write_attachments(AVFormatContext *s)
 
     for (i = 0; i < s->nb_streams; i++) {
         AVStream *st = s->streams[i];
+        mkv_track *track = &mkv->tracks[i];
         ebml_master attached_file;
-        mkv_attachment *attachment = mkv->attachments->entries;
         AVDictionaryEntry *t;
         const char *mimetype = NULL;
-        uint32_t fileuid;
 
         if (st->codecpar->codec_type != AVMEDIA_TYPE_ATTACHMENT)
             continue;
 
-        attachment = av_realloc_array(attachment, mkv->attachments->num_entries + 1, sizeof(mkv_attachment));
-        if (!attachment)
-            return AVERROR(ENOMEM);
-        mkv->attachments->entries = attachment;
-
         attached_file = start_ebml_master(dyn_cp, MATROSKA_ID_ATTACHEDFILE, 0);
 
         if (t = av_dict_get(st->metadata, "title", NULL, 0))
@@ -1708,29 +1682,10 @@  static int mkv_write_attachments(AVFormatContext *s)
             return AVERROR(EINVAL);
         }
 
-        if (s->flags & AVFMT_FLAG_BITEXACT) {
-            struct AVSHA *sha = av_sha_alloc();
-            uint8_t digest[20];
-            if (!sha)
-                return AVERROR(ENOMEM);
-            av_sha_init(sha, 160);
-            av_sha_update(sha, st->codecpar->extradata, st->codecpar->extradata_size);
-            av_sha_final(sha, digest);
-            av_free(sha);
-            fileuid = AV_RL32(digest);
-        } else {
-            fileuid = av_lfg_get(&c);
-        }
-        av_log(s, AV_LOG_VERBOSE, "Using %.8"PRIx32" for attachment %d\n",
-               fileuid, mkv->attachments->num_entries);
-
         put_ebml_string(dyn_cp, MATROSKA_ID_FILEMIMETYPE, mimetype);
         put_ebml_binary(dyn_cp, MATROSKA_ID_FILEDATA, st->codecpar->extradata, st->codecpar->extradata_size);
-        put_ebml_uint(dyn_cp, MATROSKA_ID_FILEUID, fileuid);
+        put_ebml_uint(dyn_cp, MATROSKA_ID_FILEUID, track->uid);
         end_ebml_master(dyn_cp, attached_file);
-
-        mkv->attachments->entries[mkv->attachments->num_entries].stream_idx = i;
-        mkv->attachments->entries[mkv->attachments->num_entries++].fileuid  = fileuid;
     }
     end_ebml_master_crc32(pb, &dyn_cp, mkv, MATROSKA_ID_ATTACHMENTS, 0, 0);
 
diff --git a/tests/ref/lavf/mkv_attachment b/tests/ref/lavf/mkv_attachment
index 56b1078d4a..08c9c1ebdb 100644
--- a/tests/ref/lavf/mkv_attachment
+++ b/tests/ref/lavf/mkv_attachment
@@ -1,3 +1,3 @@ 
-c339e42793d2a3cb1b8e99fc7a60de31 *tests/data/lavf/lavf.mkv_attachment
-472569 tests/data/lavf/lavf.mkv_attachment
+6f68dccaaaf875a0671f47e5b21c8cca *tests/data/lavf/lavf.mkv_attachment
+472566 tests/data/lavf/lavf.mkv_attachment
 tests/data/lavf/lavf.mkv_attachment CRC=0xec6c3c68