FFmpeg 示例-avio_dir_cmd

目录

1. 参考
2. 示例说明
3. 示例代码

1. 参考

• [1] FFmpeg/doc/examples/avio_dir_cmd.c

2. 示例说明

示例程序[1]演示了如何通过AVIOContext操作文件资源。

示例流程如下。

FFmpeg_avio_dir_cmd.png

主要函数说明：

• avio_open_dir：根据指定的路径打开文件夹。
• avio_read_dir：获取下一个文件夹中的条目。
• avio_free_directory_entry：释放在avio_read_dir()中创建的AVIODirEntry对象。
• avio_close_dir：关闭文件夹。
• avpriv_io_delete：删除一个资源。
• avpriv_io_move：移动或者重命名一个资源。

说明：

1. avio_open_dir(), avio_read_dir(), avio_free_directory_entry(), avio_close_dir()在FFmpeg的代码中除了示例程序[1]中有使用，其他地方没有使用的。
2. avpriv_io_delete()和avpriv_io_move()在libavformat/dashenc.c中有使用到。

3. 示例程序

示例程序来自[1]。

#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
#include <libavformat/avio.h>

 static const char *type_string(int type)
{
    switch (type) {
    case AVIO_ENTRY_DIRECTORY:
        return "<DIR>";
    case AVIO_ENTRY_FILE:
        return "<FILE>";
    case AVIO_ENTRY_BLOCK_DEVICE:
        return "<BLOCK DEVICE>";
    case AVIO_ENTRY_CHARACTER_DEVICE:
        return "<CHARACTER DEVICE>";
    case AVIO_ENTRY_NAMED_PIPE:
        return "<PIPE>";
    case AVIO_ENTRY_SYMBOLIC_LINK:
        return "<LINK>";
    case AVIO_ENTRY_SOCKET:
        return "<SOCKET>";
    case AVIO_ENTRY_SERVER:
        return "<SERVER>";
    case AVIO_ENTRY_SHARE:
        return "<SHARE>";
    case AVIO_ENTRY_WORKGROUP:
        return "<WORKGROUP>";
    case AVIO_ENTRY_UNKNOWN:
    default:
        break;
    }
    return "<UNKNOWN>";
}

 static int list_op(const char *input_dir)
{
    AVIODirEntry *entry = NULL;
    AVIODirContext *ctx = NULL;
    int cnt, ret;
    char filemode[4], uid_and_gid[20];

     if ((ret = avio_open_dir(&ctx, input_dir, NULL)) < 0) {
        av_log(NULL, AV_LOG_ERROR, "Cannot open directory: %s.\n", av_err2str(ret));
        goto fail;
    }

     cnt = 0;
    for (;;) {
        if ((ret = avio_read_dir(ctx, &entry)) < 0) {
            av_log(NULL, AV_LOG_ERROR, "Cannot list directory: %s.\n", av_err2str(ret));
            goto fail;
        }
        if (!entry)
            break;
        if (entry->filemode == -1) {
            snprintf(filemode, 4, "???");
        } else {
            snprintf(filemode, 4, "%3"PRIo64, entry->filemode);
        }
        snprintf(uid_and_gid, 20, "%"PRId64"(%"PRId64")", entry->user_id, entry->group_id);
        if (cnt == 0)
            av_log(NULL, AV_LOG_INFO, "%-9s %12s %30s %10s %s %16s %16s %16s\n",
                   "TYPE", "SIZE", "NAME", "UID(GID)", "UGO", "MODIFIED",
                   "ACCESSED", "STATUS_CHANGED");
        av_log(NULL, AV_LOG_INFO, "%-9s %12"PRId64" %30s %10s %s %16"PRId64" %16"PRId64" %16"PRId64"\n",
               type_string(entry->type),
               entry->size,
               entry->name,
               uid_and_gid,
               filemode,
               entry->modification_timestamp,
               entry->access_timestamp,
               entry->status_change_timestamp);
        avio_free_directory_entry(&entry);
        cnt++;
    };

   fail:
    avio_close_dir(&ctx);
    return ret;
}

 static int del_op(const char *url)
{
    int ret = avpriv_io_delete(url);
    if (ret < 0)
        av_log(NULL, AV_LOG_ERROR, "Cannot delete '%s': %s.\n", url, av_err2str(ret));
    return ret;
}

 static int move_op(const char *src, const char *dst)
{
    int ret = avpriv_io_move(src, dst);
    if (ret < 0)
        av_log(NULL, AV_LOG_ERROR, "Cannot move '%s' into '%s': %s.\n", src, dst, av_err2str(ret));
    return ret;
}


 static void usage(const char *program_name)
{
    fprintf(stderr, "usage: %s OPERATION entry1 [entry2]\n"
            "API example program to show how to manipulate resources "
            "accessed through AVIOContext.\n"
            "OPERATIONS:\n"
            "list      list content of the directory\n"
            "move      rename content in directory\n"
            "del       delete content in directory\n",
            program_name);
}

 int main(int argc, char *argv[])
{
    const char *op = NULL;
    int ret;

     av_log_set_level(AV_LOG_DEBUG);

     if (argc < 2) {
        usage(argv[0]);
        return 1;
    }

     op = argv[1];
    if (strcmp(op, "list") == 0) {
        if (argc < 3) {
            av_log(NULL, AV_LOG_INFO, "Missing argument for list operation.\n");
            ret = AVERROR(EINVAL);
        } else {
            ret = list_op(argv[2]);
        }
    } else if (strcmp(op, "del") == 0) {
        if (argc < 3) {
            av_log(NULL, AV_LOG_INFO, "Missing argument for del operation.\n");
            ret = AVERROR(EINVAL);
        } else {
            ret = del_op(argv[2]);
        }
    } else if (strcmp(op, "move") == 0) {
        if (argc < 4) {
            av_log(NULL, AV_LOG_INFO, "Missing argument for move operation.\n");
            ret = AVERROR(EINVAL);
        } else {
            ret = move_op(argv[2], argv[3]);
        }
    } else {
        av_log(NULL, AV_LOG_INFO, "Invalid operation %s\n", op);
        ret = AVERROR(EINVAL);
    }

     return ret < 0 ? 1 : 0;
}

通过示例获取文件夹中的文件列表信息的输出结果如下所示。

avio_dir_cmd_output.PNG