[FFmpeg-devel] [PATCH 2/3] Add av_load_index_file and av_save_index_file

[Michael Chinen]

On Thu, Aug 19, 2010 at 12:29 PM, Michael Niedermayer <michaelni at gmx.at> wrote:
> On Thu, Aug 19, 2010 at 11:29:01AM +0200, Michael Chinen wrote:
>> On Tue, Aug 17, 2010 at 2:07 PM, Michael Niedermayer <michaelni at gmx.at> wrote:
>> [...]
>> >> +/**
>> >> + * Save the flags, size, and differences for the index table
>> >> + */
>> >> +#define FF_SAVEINDEX_PACKETSIZE 1000
>> >> +static int av_save_index_stream(ByteIOContext *bc, AVStream *st,
>> >> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?AVFormatContext *ic) {
>> >> + ? ?AVIndexEntry start_ie;
>> >> + ? ?AVIndexEntry *last_ie, *curr_ie;
>> >> + ? ?int i;
>> >> +
>> >> + ? ?//we may need to save something like codec id to be safe.
>> >> + ? ?ff_put_v(bc, st->seek_table_flags);
>> >> + ? ?//we only write the index if we have a finished table.
>> >> + ? ?if (st->seek_table_flags & AV_SEEKTABLE_FINISHED) {
>> >> + ? ? ? ?ff_put_v(bc, st->nb_index_entries);
>> >> +
>> >> + ? ? ? ?memset(&start_ie, 0, sizeof(AVIndexEntry));
>> >> + ? ? ? ?last_ie = &start_ie;
>> >> + ? ? ? ?for (i = 0; i < st->nb_index_entries; i++) {
>> >> + ? ? ? ? ? ?curr_ie = &st->index_entries[i];
>> >
>> >> + ? ? ? ? ? ?ff_put_v(bc, curr_ie->pos - last_ie->pos);
>> >> + ? ? ? ? ? ?ff_put_v(bc, curr_ie->timestamp - last_ie->timestamp);
>> >> + ? ? ? ? ? ?ff_put_v(bc, curr_ie->flags - last_ie->flags);
>> >> + ? ? ? ? ? ?ff_put_v(bc, curr_ie->size - last_ie->size);
>> >> + ? ? ? ? ? ?ff_put_v(bc, curr_ie->min_distance - last_ie->min_distance);
>> >
>> > vertical align please
>>
>> done.
>>
>> >
>> >
>> >> + ? ? ? ? ? ?last_ie = curr_ie;
>> >
>> >> + ? ? ? ? ? ?if (i % FF_SAVEINDEX_PACKETSIZE == 0)
>> >> + ? ? ? ? ? ? ? ?put_flush_packet(bc);
>> >
>> > why?
>>
>> Unfamiliarity. ?Removed.
>>
>> >
>> >
>> > [...]
>> >
>> >> +static int av_load_index(ByteIOContext *bc, AVFormatContext *ic) {
>> >> + ? ?int i, ret;
>> >> + ? ?uint64_t v;
>> >> + ? ?char read_str[256];
>> >> +
>> >> + ? ?get_strz(bc, read_str, 255);
>> >
>> > s/255/sizeof()/
>>
>> Done.
>>
>> Michael
>
>> ?avformat.h | ? 12 ++++
>> ?utils.c ? ?| ?167 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>> ?2 files changed, 179 insertions(+)
>> a7ff3f38a534c051b0d450ed379f005ad310311d ?0002-Add-av_load_index_file-and-av_save_index_file.patch
>> From de8ad0accaaa6110430c52e28aef6418024bba2c Mon Sep 17 00:00:00 2001
>> From: Michael Chinen <mchinen at gmail.com>
>> Date: Thu, 19 Aug 2010 10:49:03 +0200
>> Subject: [PATCH 2/3] Add av_load_index_file and av_save_index_file
>>
>> 2nd Submission - MN's review:
>> remove packet flushing
>> stylistic changes
>> ---
>> ?libavformat/avformat.h | ? 12 ++++
>> ?libavformat/utils.c ? ?| ?167 ++++++++++++++++++++++++++++++++++++++++++++++++
>> ?2 files changed, 179 insertions(+), 0 deletions(-)
>>
>> diff --git a/libavformat/avformat.h b/libavformat/avformat.h
>> index 6aeb460..5785f3a 100644
>> --- a/libavformat/avformat.h
>> +++ b/libavformat/avformat.h
>> @@ -1243,6 +1243,18 @@ int av_build_index(AVFormatContext *s, int flags);
>> ?#define AV_BUILD_INDEX_USE_CBR ?0x0002 ///< Detect and use CBR instead of index seeking
>>
>> ?/**
>> + * Saves the index table built with av_build_index to a file.
>> + * @return 0 if succesful or a negative value on failure.
>> + */
>> +int av_save_index_file(AVFormatContext *ic, const char *filename);
>> +
>> +/**
>> + * Loads the index saved with av_save_index.
>> + * @return 0 if successful or a negative value on failure.
>> + */
>> +int av_load_index_file(AVFormatContext *ic, const char *filename);
>> +
>> +/**
>> ? * Ensure the index uses less memory than the maximum specified in
>> ? * AVFormatContext.max_index_size by discarding entries if it grows
>> ? * too large.
>> diff --git a/libavformat/utils.c b/libavformat/utils.c
>> index cc893f6..5633df6 100644
>> --- a/libavformat/utils.c
>> +++ b/libavformat/utils.c
>> @@ -1822,6 +1822,173 @@ int avformat_seek_file(AVFormatContext *s, int stream_index, int64_t min_ts, int
>> ? ? ?// try some generic seek like av_seek_frame_generic() but with new ts semantics
>> ?}
>>
>> +/**
>> + * Save the flags, size, and differences for the index table
>> + */
>> +static int av_save_index_stream(ByteIOContext *bc, AVStream *st,
>> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?AVFormatContext *ic) {
>> + ? ?AVIndexEntry start_ie;
>> + ? ?AVIndexEntry *last_ie, *curr_ie;
>> + ? ?int i;
>> +
>> + ? ?//we may need to save something like codec id to be safe.
>> + ? ?ff_put_v(bc, st->seek_table_flags);
>> + ? ?//we only write the index if we have a finished table.
>> + ? ?if (st->seek_table_flags & AV_SEEKTABLE_FINISHED) {
>> + ? ? ? ?ff_put_v(bc, st->nb_index_entries);
>> +
>> + ? ? ? ?memset(&start_ie, 0, sizeof(AVIndexEntry));
>> + ? ? ? ?last_ie = &start_ie;
>> + ? ? ? ?for (i = 0; i < st->nb_index_entries; i++) {
>> + ? ? ? ? ? ?curr_ie = &st->index_entries[i];
>> + ? ? ? ? ? ?ff_put_v(bc, curr_ie->pos ? ? ? ? ?- last_ie->pos);
>> + ? ? ? ? ? ?ff_put_v(bc, curr_ie->timestamp ? ?- last_ie->timestamp);
>> + ? ? ? ? ? ?ff_put_v(bc, curr_ie->flags ? ? ? ?- last_ie->flags);
>> + ? ? ? ? ? ?ff_put_v(bc, curr_ie->size ? ? ? ? - last_ie->size);
>> + ? ? ? ? ? ?ff_put_v(bc, curr_ie->min_distance - last_ie->min_distance);
>> + ? ? ? ? ? ?last_ie = curr_ie;
>> + ? ? ? ?}
>> + ? ? ? ?av_log(ic, AV_LOG_DEBUG,
>> + ? ? ? ? ? ? ? "successfully wrote index stream with %i entries.\n",
>> + ? ? ? ? ? ? ? st->nb_index_entries);
>> + ? ?}
>> + ? ?put_flush_packet(bc);
>> +
>> + ? ?return 0;
>> +}
>
> theres a race condition if 2 applications are run and one tries to load an
> index that hasnt been finished yet.
> this risk can be avoided by seeking back once its all finished and setting
> some flag at the begin.
> this could still leave a issue with 2 applications trying to write the same
> index at the same time, this needs O_EXCL to be passed to open() and thus
> requires a bit of api extension to pass this through

Okay, I did this the byte setting lock for now.

Also I am going backpacking from Sept.1 to 24 without so much planned
net access.  I will keep up with these patches after I get back but
want I'd like to get as much of my patches reviewed as possible.

Michael
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 0002-Add-av_load_index_file-and-av_save_index_file.patch
Type: application/octet-stream
Size: 7761 bytes
Desc: not available
URL: <http://lists.mplayerhq.hu/pipermail/ffmpeg-devel/attachments/20100822/c698d0cf/attachment.obj>